diff --git a/.clang-tidy b/.clang-tidy
index a240e9c67e..a5206795b0 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -11,7 +11,6 @@ misc-*,\
 -misc-static-assert,\
 modernize-*,\
 -modernize-avoid-c-arrays,\
--modernize-deprecated-headers,\
 -modernize-use-nodiscard,\
 -modernize-use-noexcept,\
 -modernize-use-transparent-functors,\
diff --git a/Source/CPack/IFW/cmCPackIFWInstaller.cxx b/Source/CPack/IFW/cmCPackIFWInstaller.cxx
index b4bfea778e..2393279e9d 100644
--- a/Source/CPack/IFW/cmCPackIFWInstaller.cxx
+++ b/Source/CPack/IFW/cmCPackIFWInstaller.cxx
@@ -13,8 +13,8 @@
 #include "cmXMLParser.h"
 #include "cmXMLWriter.h"
 
+#include <cstddef>
 #include <sstream>
-#include <stddef.h>
 #include <utility>
 
 cmCPackIFWInstaller::cmCPackIFWInstaller() = default;
diff --git a/Source/CPack/IFW/cmCPackIFWPackage.cxx b/Source/CPack/IFW/cmCPackIFWPackage.cxx
index 5fa8ccedfb..9f2a443f69 100644
--- a/Source/CPack/IFW/cmCPackIFWPackage.cxx
+++ b/Source/CPack/IFW/cmCPackIFWPackage.cxx
@@ -13,9 +13,9 @@
 #include "cmTimestamp.h"
 #include "cmXMLWriter.h"
 
+#include <cstddef>
 #include <map>
 #include <sstream>
-#include <stddef.h>
 #include <utility>
 
 //---------------------------------------------------------- CompareStruct ---
diff --git a/Source/CPack/IFW/cmCPackIFWRepository.cxx b/Source/CPack/IFW/cmCPackIFWRepository.cxx
index 8042167edb..82ddbdbd80 100644
--- a/Source/CPack/IFW/cmCPackIFWRepository.cxx
+++ b/Source/CPack/IFW/cmCPackIFWRepository.cxx
@@ -8,7 +8,7 @@
 #include "cmXMLParser.h"
 #include "cmXMLWriter.h"
 
-#include <stddef.h>
+#include <cstddef>
 
 cmCPackIFWRepository::cmCPackIFWRepository()
   : Update(cmCPackIFWRepository::None)
diff --git a/Source/CPack/OSXScriptLauncher.cxx b/Source/CPack/OSXScriptLauncher.cxx
index 00d272c833..b8f12fd3aa 100644
--- a/Source/CPack/OSXScriptLauncher.cxx
+++ b/Source/CPack/OSXScriptLauncher.cxx
@@ -3,8 +3,9 @@
 #include "cmsys/FStream.hxx"
 #include "cmsys/Process.h"
 #include "cmsys/SystemTools.hxx"
+
+#include <cstddef>
 #include <iostream>
-#include <stddef.h>
 #include <string>
 #include <vector>
 
diff --git a/Source/CPack/cmCPackDebGenerator.cxx b/Source/CPack/cmCPackDebGenerator.cxx
index cefbc909ec..0e64b5a86d 100644
--- a/Source/CPack/cmCPackDebGenerator.cxx
+++ b/Source/CPack/cmCPackDebGenerator.cxx
@@ -13,10 +13,10 @@
 #include "cm_sys_stat.h"
 
 #include "cmsys/Glob.hxx"
+#include <cstring>
 #include <map>
 #include <ostream>
 #include <set>
-#include <string.h>
 #include <utility>
 
 namespace {
diff --git a/Source/CPack/cmCPackDragNDropGenerator.cxx b/Source/CPack/cmCPackDragNDropGenerator.cxx
index ca06b816c2..bedbfa80b0 100644
--- a/Source/CPack/cmCPackDragNDropGenerator.cxx
+++ b/Source/CPack/cmCPackDragNDropGenerator.cxx
@@ -12,9 +12,9 @@
 #include "cmsys/FStream.hxx"
 #include "cmsys/RegularExpression.hxx"
 #include <algorithm>
+#include <cstdlib>
 #include <iomanip>
 #include <map>
-#include <stdlib.h>
 
 #include <CoreFoundation/CoreFoundation.h>
 
diff --git a/Source/CPack/cmCPackNSISGenerator.cxx b/Source/CPack/cmCPackNSISGenerator.cxx
index 8098edfd7c..3f531860d8 100644
--- a/Source/CPack/cmCPackNSISGenerator.cxx
+++ b/Source/CPack/cmCPackNSISGenerator.cxx
@@ -14,10 +14,10 @@
 #include "cmsys/Directory.hxx"
 #include "cmsys/RegularExpression.hxx"
 #include <algorithm>
+#include <cstdlib>
+#include <cstring>
 #include <map>
 #include <sstream>
-#include <stdlib.h>
-#include <string.h>
 #include <utility>
 
 /* NSIS uses different command line syntax on Windows and others */
diff --git a/Source/CPack/cmCPackPackageMakerGenerator.cxx b/Source/CPack/cmCPackPackageMakerGenerator.cxx
index 5dc36abe0e..7be6a7d1f5 100644
--- a/Source/CPack/cmCPackPackageMakerGenerator.cxx
+++ b/Source/CPack/cmCPackPackageMakerGenerator.cxx
@@ -4,11 +4,11 @@
 
 #include "cmsys/FStream.hxx"
 #include "cmsys/RegularExpression.hxx"
-#include <assert.h>
+#include <cassert>
+#include <cstdio>
+#include <cstdlib>
 #include <map>
 #include <sstream>
-#include <stdio.h>
-#include <stdlib.h>
 #include <string>
 
 #include "cmCPackComponentGroup.h"
diff --git a/Source/CPack/cmCPackProductBuildGenerator.cxx b/Source/CPack/cmCPackProductBuildGenerator.cxx
index 800af283d0..dae268c5ce 100644
--- a/Source/CPack/cmCPackProductBuildGenerator.cxx
+++ b/Source/CPack/cmCPackProductBuildGenerator.cxx
@@ -2,9 +2,9 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmCPackProductBuildGenerator.h"
 
+#include <cstddef>
 #include <map>
 #include <sstream>
-#include <stddef.h>
 
 #include "cmCPackComponentGroup.h"
 #include "cmCPackLog.h"
diff --git a/Source/CPack/cmCPackRPMGenerator.cxx b/Source/CPack/cmCPackRPMGenerator.cxx
index e8728a35e3..0c1cecf39c 100644
--- a/Source/CPack/cmCPackRPMGenerator.cxx
+++ b/Source/CPack/cmCPackRPMGenerator.cxx
@@ -3,7 +3,7 @@
 #include "cmCPackRPMGenerator.h"
 
 #include <algorithm>
-#include <ctype.h>
+#include <cctype>
 #include <map>
 #include <ostream>
 #include <utility>
diff --git a/Source/CPack/cmCPackSTGZGenerator.cxx b/Source/CPack/cmCPackSTGZGenerator.cxx
index 3092508a6f..eb48c378cb 100644
--- a/Source/CPack/cmCPackSTGZGenerator.cxx
+++ b/Source/CPack/cmCPackSTGZGenerator.cxx
@@ -3,8 +3,8 @@
 #include "cmCPackSTGZGenerator.h"
 
 #include "cmsys/FStream.hxx"
+#include <cstdio>
 #include <sstream>
-#include <stdio.h>
 #include <string>
 #include <vector>
 
diff --git a/Source/CPack/cpack.cxx b/Source/CPack/cpack.cxx
index 08681ec260..ab44a42611 100644
--- a/Source/CPack/cpack.cxx
+++ b/Source/CPack/cpack.cxx
@@ -22,10 +22,10 @@
 #  include "cmsys/ConsoleBuf.hxx"
 #endif
 
+#include <cstddef>
 #include <iostream>
 #include <map>
 #include <sstream>
-#include <stddef.h>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/Source/CTest/cmCTestBZR.cxx b/Source/CTest/cmCTestBZR.cxx
index 52dc0ac21d..4ea0c88791 100644
--- a/Source/CTest/cmCTestBZR.cxx
+++ b/Source/CTest/cmCTestBZR.cxx
@@ -11,10 +11,10 @@
 
 #include "cm_expat.h"
 #include "cmsys/RegularExpression.hxx"
+#include <cstdlib>
 #include <list>
 #include <map>
 #include <ostream>
-#include <stdlib.h>
 #include <vector>
 
 extern "C" int cmBZRXMLParserUnknownEncodingHandler(void* /*unused*/,
diff --git a/Source/CTest/cmCTestBuildAndTestHandler.cxx b/Source/CTest/cmCTestBuildAndTestHandler.cxx
index e7fb4c7dcb..0f79670144 100644
--- a/Source/CTest/cmCTestBuildAndTestHandler.cxx
+++ b/Source/CTest/cmCTestBuildAndTestHandler.cxx
@@ -14,9 +14,9 @@
 
 #include "cmsys/Process.h"
 #include <chrono>
+#include <cstdlib>
 #include <cstring>
 #include <ratio>
-#include <stdlib.h>
 
 cmCTestBuildAndTestHandler::cmCTestBuildAndTestHandler()
 {
diff --git a/Source/CTest/cmCTestBuildCommand.cxx b/Source/CTest/cmCTestBuildCommand.cxx
index cb22fa634c..02b00e3dfe 100644
--- a/Source/CTest/cmCTestBuildCommand.cxx
+++ b/Source/CTest/cmCTestBuildCommand.cxx
@@ -11,8 +11,8 @@
 #include "cmSystemTools.h"
 #include "cmake.h"
 
+#include <cstring>
 #include <sstream>
-#include <string.h>
 
 class cmExecutionStatus;
 
diff --git a/Source/CTest/cmCTestBuildHandler.cxx b/Source/CTest/cmCTestBuildHandler.cxx
index e07d7aa6e2..86abb124c0 100644
--- a/Source/CTest/cmCTestBuildHandler.cxx
+++ b/Source/CTest/cmCTestBuildHandler.cxx
@@ -17,9 +17,9 @@
 #include "cmsys/Directory.hxx"
 #include "cmsys/FStream.hxx"
 #include "cmsys/Process.h"
+#include <cstdlib>
+#include <cstring>
 #include <set>
-#include <stdlib.h>
-#include <string.h>
 #include <utility>
 
 static const char* cmCTestErrorMatches[] = {
diff --git a/Source/CTest/cmCTestConfigureCommand.cxx b/Source/CTest/cmCTestConfigureCommand.cxx
index 320c1842bf..8a56f3dcf5 100644
--- a/Source/CTest/cmCTestConfigureCommand.cxx
+++ b/Source/CTest/cmCTestConfigureCommand.cxx
@@ -10,8 +10,8 @@
 #include "cmSystemTools.h"
 #include "cmake.h"
 
+#include <cstring>
 #include <sstream>
-#include <string.h>
 #include <vector>
 
 cmCTestConfigureCommand::cmCTestConfigureCommand()
diff --git a/Source/CTest/cmCTestCoverageHandler.cxx b/Source/CTest/cmCTestCoverageHandler.cxx
index d9dd931beb..4d7638766a 100644
--- a/Source/CTest/cmCTestCoverageHandler.cxx
+++ b/Source/CTest/cmCTestCoverageHandler.cxx
@@ -24,12 +24,12 @@
 #include "cmsys/RegularExpression.hxx"
 #include <algorithm>
 #include <chrono>
+#include <cstdio>
+#include <cstdlib>
 #include <cstring>
 #include <iomanip>
 #include <iterator>
 #include <sstream>
-#include <stdio.h>
-#include <stdlib.h>
 #include <utility>
 
 class cmMakefile;
diff --git a/Source/CTest/cmCTestCurl.cxx b/Source/CTest/cmCTestCurl.cxx
index 40f5918c07..87932607ea 100644
--- a/Source/CTest/cmCTestCurl.cxx
+++ b/Source/CTest/cmCTestCurl.cxx
@@ -8,8 +8,8 @@
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 
+#include <cstdio>
 #include <ostream>
-#include <stdio.h>
 
 cmCTestCurl::cmCTestCurl(cmCTest* ctest)
 {
diff --git a/Source/CTest/cmCTestGIT.cxx b/Source/CTest/cmCTestGIT.cxx
index 3ae464dba2..9fd3a6223d 100644
--- a/Source/CTest/cmCTestGIT.cxx
+++ b/Source/CTest/cmCTestGIT.cxx
@@ -4,10 +4,10 @@
 
 #include "cmsys/FStream.hxx"
 #include "cmsys/Process.h"
-#include <ctype.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <time.h>
+#include <cctype>
+#include <cstdio>
+#include <cstdlib>
+#include <ctime>
 #include <vector>
 
 #include "cmCTest.h"
diff --git a/Source/CTest/cmCTestHandlerCommand.cxx b/Source/CTest/cmCTestHandlerCommand.cxx
index 6add71786c..9c5425d71a 100644
--- a/Source/CTest/cmCTestHandlerCommand.cxx
+++ b/Source/CTest/cmCTestHandlerCommand.cxx
@@ -10,9 +10,9 @@
 #include "cmSystemTools.h"
 #include "cmWorkingDirectory.h"
 
+#include <cstdlib>
 #include <cstring>
 #include <sstream>
-#include <stdlib.h>
 
 cmCTestHandlerCommand::cmCTestHandlerCommand()
 {
diff --git a/Source/CTest/cmCTestLaunch.cxx b/Source/CTest/cmCTestLaunch.cxx
index ac52581fe5..ba49c29101 100644
--- a/Source/CTest/cmCTestLaunch.cxx
+++ b/Source/CTest/cmCTestLaunch.cxx
@@ -5,9 +5,9 @@
 #include "cmsys/FStream.hxx"
 #include "cmsys/Process.h"
 #include "cmsys/RegularExpression.hxx"
+#include <cstdlib>
+#include <cstring>
 #include <iostream>
-#include <stdlib.h>
-#include <string.h>
 
 #include "cmCryptoHash.h"
 #include "cmGeneratedFileStream.h"
diff --git a/Source/CTest/cmCTestMemCheckHandler.cxx b/Source/CTest/cmCTestMemCheckHandler.cxx
index 259240f8a9..ba196f0e48 100644
--- a/Source/CTest/cmCTestMemCheckHandler.cxx
+++ b/Source/CTest/cmCTestMemCheckHandler.cxx
@@ -12,9 +12,9 @@
 #include "cmsys/Glob.hxx"
 #include "cmsys/RegularExpression.hxx"
 #include <chrono>
+#include <cstring>
 #include <iostream>
 #include <sstream>
-#include <string.h>
 #include <utility>
 
 struct CatToErrorType
diff --git a/Source/CTest/cmCTestMultiProcessHandler.cxx b/Source/CTest/cmCTestMultiProcessHandler.cxx
index af1980a060..f79ba2e67f 100644
--- a/Source/CTest/cmCTestMultiProcessHandler.cxx
+++ b/Source/CTest/cmCTestMultiProcessHandler.cxx
@@ -25,15 +25,15 @@
 
 #include <algorithm>
 #include <chrono>
+#include <cmath>
+#include <cstdlib>
 #include <cstring>
 #include <iomanip>
 #include <iostream>
 #include <list>
-#include <math.h>
 #include <memory>
 #include <sstream>
 #include <stack>
-#include <stdlib.h>
 #include <unordered_map>
 #include <utility>
 #include <vector>
diff --git a/Source/CTest/cmCTestP4.cxx b/Source/CTest/cmCTestP4.cxx
index 08c850d49f..a6aea85d34 100644
--- a/Source/CTest/cmCTestP4.cxx
+++ b/Source/CTest/cmCTestP4.cxx
@@ -12,8 +12,8 @@
 
 #include "cmsys/RegularExpression.hxx"
 #include <algorithm>
+#include <ctime>
 #include <ostream>
-#include <time.h>
 #include <utility>
 
 cmCTestP4::cmCTestP4(cmCTest* ct, std::ostream& log)
diff --git a/Source/CTest/cmCTestRunTest.cxx b/Source/CTest/cmCTestRunTest.cxx
index c5bb826136..3629a50c26 100644
--- a/Source/CTest/cmCTestRunTest.cxx
+++ b/Source/CTest/cmCTestRunTest.cxx
@@ -13,11 +13,11 @@
 #include "cmsys/RegularExpression.hxx"
 #include <chrono>
 #include <cstdint>
+#include <cstdio>
 #include <cstring>
 #include <iomanip>
 #include <ratio>
 #include <sstream>
-#include <stdio.h>
 #include <utility>
 
 #include "cm_memory.hxx"
diff --git a/Source/CTest/cmCTestSVN.cxx b/Source/CTest/cmCTestSVN.cxx
index a945111e5e..6e5b5e72e7 100644
--- a/Source/CTest/cmCTestSVN.cxx
+++ b/Source/CTest/cmCTestSVN.cxx
@@ -12,10 +12,10 @@
 #include "cmXMLWriter.h"
 
 #include "cmsys/RegularExpression.hxx"
+#include <cstdlib>
+#include <cstring>
 #include <map>
 #include <ostream>
-#include <stdlib.h>
-#include <string.h>
 
 struct cmCTestSVN::Revision : public cmCTestVC::Revision
 {
diff --git a/Source/CTest/cmCTestScriptHandler.cxx b/Source/CTest/cmCTestScriptHandler.cxx
index 81966dd238..354e3c4188 100644
--- a/Source/CTest/cmCTestScriptHandler.cxx
+++ b/Source/CTest/cmCTestScriptHandler.cxx
@@ -34,13 +34,13 @@
 #include "cmSystemTools.h"
 #include "cmake.h"
 
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
 #include <map>
 #include <memory>
 #include <ratio>
 #include <sstream>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
 #include <utility>
 
 #ifdef _WIN32
diff --git a/Source/CTest/cmCTestSleepCommand.cxx b/Source/CTest/cmCTestSleepCommand.cxx
index 2752cd3703..bc4470c736 100644
--- a/Source/CTest/cmCTestSleepCommand.cxx
+++ b/Source/CTest/cmCTestSleepCommand.cxx
@@ -4,7 +4,7 @@
 
 #include "cmCTestScriptHandler.h"
 
-#include <stdlib.h>
+#include <cstdlib>
 
 class cmExecutionStatus;
 
diff --git a/Source/CTest/cmCTestStartCommand.cxx b/Source/CTest/cmCTestStartCommand.cxx
index e4a184426e..844f2ca760 100644
--- a/Source/CTest/cmCTestStartCommand.cxx
+++ b/Source/CTest/cmCTestStartCommand.cxx
@@ -8,8 +8,8 @@
 #include "cmMakefile.h"
 #include "cmSystemTools.h"
 
+#include <cstddef>
 #include <sstream>
-#include <stddef.h>
 
 class cmExecutionStatus;
 
diff --git a/Source/CTest/cmCTestSubmitHandler.cxx b/Source/CTest/cmCTestSubmitHandler.cxx
index f215911927..ca7fd2c439 100644
--- a/Source/CTest/cmCTestSubmitHandler.cxx
+++ b/Source/CTest/cmCTestSubmitHandler.cxx
@@ -6,9 +6,9 @@
 #include "cm_jsoncpp_reader.h"
 #include "cm_jsoncpp_value.h"
 #include <chrono>
+#include <cstdio>
+#include <cstdlib>
 #include <sstream>
-#include <stdio.h>
-#include <stdlib.h>
 
 #include "cmAlgorithms.h"
 #include "cmCTest.h"
diff --git a/Source/CTest/cmCTestTestCommand.cxx b/Source/CTest/cmCTestTestCommand.cxx
index 24de5b4034..3a29ad3a0e 100644
--- a/Source/CTest/cmCTestTestCommand.cxx
+++ b/Source/CTest/cmCTestTestCommand.cxx
@@ -10,8 +10,8 @@
 #include "cmStringAlgorithms.h"
 
 #include <chrono>
+#include <cstdlib>
 #include <sstream>
-#include <stdlib.h>
 #include <vector>
 
 cmCTestTestCommand::cmCTestTestCommand()
diff --git a/Source/CTest/cmCTestTestHandler.cxx b/Source/CTest/cmCTestTestHandler.cxx
index f0c5939dd4..10f9f9b172 100644
--- a/Source/CTest/cmCTestTestHandler.cxx
+++ b/Source/CTest/cmCTestTestHandler.cxx
@@ -29,15 +29,15 @@
 #include <cmsys/Directory.hxx>
 #include <cmsys/RegularExpression.hxx>
 #include <cstddef>
+#include <cstdio>
+#include <cstdlib>
 #include <cstring>
+#include <ctime>
 #include <functional>
 #include <iomanip>
 #include <iterator>
 #include <set>
 #include <sstream>
-#include <stdio.h>
-#include <stdlib.h>
-#include <time.h>
 #include <utility>
 
 namespace {
diff --git a/Source/CTest/cmCTestVC.cxx b/Source/CTest/cmCTestVC.cxx
index 773886d958..00919e530b 100644
--- a/Source/CTest/cmCTestVC.cxx
+++ b/Source/CTest/cmCTestVC.cxx
@@ -8,9 +8,9 @@
 #include "cmXMLWriter.h"
 
 #include "cmsys/Process.h"
+#include <cstdio>
+#include <ctime>
 #include <sstream>
-#include <stdio.h>
-#include <time.h>
 #include <vector>
 
 cmCTestVC::cmCTestVC(cmCTest* ct, std::ostream& log)
diff --git a/Source/CTest/cmParseBlanketJSCoverage.cxx b/Source/CTest/cmParseBlanketJSCoverage.cxx
index 191100c260..8c87700b49 100644
--- a/Source/CTest/cmParseBlanketJSCoverage.cxx
+++ b/Source/CTest/cmParseBlanketJSCoverage.cxx
@@ -7,8 +7,8 @@
 #include "cmSystemTools.h"
 
 #include "cmsys/FStream.hxx"
-#include <stdio.h>
-#include <stdlib.h>
+#include <cstdio>
+#include <cstdlib>
 
 class cmParseBlanketJSCoverage::JSONParser
 {
diff --git a/Source/CTest/cmParseCacheCoverage.cxx b/Source/CTest/cmParseCacheCoverage.cxx
index b3ef7d3140..da486107a9 100644
--- a/Source/CTest/cmParseCacheCoverage.cxx
+++ b/Source/CTest/cmParseCacheCoverage.cxx
@@ -7,9 +7,9 @@
 
 #include "cmsys/Directory.hxx"
 #include "cmsys/FStream.hxx"
+#include <cstdio>
+#include <cstdlib>
 #include <map>
-#include <stdio.h>
-#include <stdlib.h>
 #include <utility>
 
 cmParseCacheCoverage::cmParseCacheCoverage(
diff --git a/Source/CTest/cmParseCoberturaCoverage.cxx b/Source/CTest/cmParseCoberturaCoverage.cxx
index e4f353b68a..7c00d0043b 100644
--- a/Source/CTest/cmParseCoberturaCoverage.cxx
+++ b/Source/CTest/cmParseCoberturaCoverage.cxx
@@ -7,8 +7,8 @@
 #include "cmXMLParser.h"
 
 #include "cmsys/FStream.hxx"
-#include <stdlib.h>
-#include <string.h>
+#include <cstdlib>
+#include <cstring>
 
 class cmParseCoberturaCoverage::XMLParser : public cmXMLParser
 {
diff --git a/Source/CTest/cmParseDelphiCoverage.cxx b/Source/CTest/cmParseDelphiCoverage.cxx
index e8a184ab57..22c756ca42 100644
--- a/Source/CTest/cmParseDelphiCoverage.cxx
+++ b/Source/CTest/cmParseDelphiCoverage.cxx
@@ -6,8 +6,8 @@
 
 #include "cmsys/FStream.hxx"
 #include "cmsys/Glob.hxx"
-#include <stdio.h>
-#include <stdlib.h>
+#include <cstdio>
+#include <cstdlib>
 
 class cmParseDelphiCoverage::HTMLParser
 {
diff --git a/Source/CTest/cmParseGTMCoverage.cxx b/Source/CTest/cmParseGTMCoverage.cxx
index 621ca791a7..1f2181bed2 100644
--- a/Source/CTest/cmParseGTMCoverage.cxx
+++ b/Source/CTest/cmParseGTMCoverage.cxx
@@ -7,9 +7,9 @@
 
 #include "cmsys/Directory.hxx"
 #include "cmsys/FStream.hxx"
+#include <cstdio>
+#include <cstdlib>
 #include <map>
-#include <stdio.h>
-#include <stdlib.h>
 #include <vector>
 
 cmParseGTMCoverage::cmParseGTMCoverage(cmCTestCoverageHandlerContainer& cont,
diff --git a/Source/CTest/cmParseJacocoCoverage.cxx b/Source/CTest/cmParseJacocoCoverage.cxx
index 6a2d0cc2e5..be6348a749 100644
--- a/Source/CTest/cmParseJacocoCoverage.cxx
+++ b/Source/CTest/cmParseJacocoCoverage.cxx
@@ -9,8 +9,8 @@
 #include "cmsys/Directory.hxx"
 #include "cmsys/FStream.hxx"
 #include "cmsys/Glob.hxx"
-#include <stdlib.h>
-#include <string.h>
+#include <cstdlib>
+#include <cstring>
 
 class cmParseJacocoCoverage::XMLParser : public cmXMLParser
 {
diff --git a/Source/CTest/cmParsePHPCoverage.cxx b/Source/CTest/cmParsePHPCoverage.cxx
index 870e2229ef..8f0404dcbe 100644
--- a/Source/CTest/cmParsePHPCoverage.cxx
+++ b/Source/CTest/cmParsePHPCoverage.cxx
@@ -7,8 +7,8 @@
 
 #include "cmsys/Directory.hxx"
 #include "cmsys/FStream.hxx"
-#include <stdlib.h>
-#include <string.h>
+#include <cstdlib>
+#include <cstring>
 
 /*
   To setup coverage for php.
diff --git a/Source/CTest/cmProcess.cxx b/Source/CTest/cmProcess.cxx
index 61d2ed348f..9c63a59a9a 100644
--- a/Source/CTest/cmProcess.cxx
+++ b/Source/CTest/cmProcess.cxx
@@ -10,8 +10,8 @@
 #include "cmStringAlgorithms.h"
 #include "cmsys/Process.h"
 
+#include <csignal>
 #include <iostream>
-#include <signal.h>
 #include <string>
 #if defined(_WIN32)
 #  include "cm_kwiml.h"
diff --git a/Source/CursesDialog/ccmake.cxx b/Source/CursesDialog/ccmake.cxx
index ce328984f6..567b4f48fe 100644
--- a/Source/CursesDialog/ccmake.cxx
+++ b/Source/CursesDialog/ccmake.cxx
@@ -11,9 +11,9 @@
 #include "cmake.h"
 
 #include "cmsys/Encoding.hxx"
+#include <csignal>
+#include <cstring>
 #include <iostream>
-#include <signal.h>
-#include <string.h>
 #include <string>
 #include <vector>
 
diff --git a/Source/CursesDialog/cmCursesCacheEntryComposite.cxx b/Source/CursesDialog/cmCursesCacheEntryComposite.cxx
index f450a1c0e4..47fe84cfe4 100644
--- a/Source/CursesDialog/cmCursesCacheEntryComposite.cxx
+++ b/Source/CursesDialog/cmCursesCacheEntryComposite.cxx
@@ -15,7 +15,7 @@
 #include "cmSystemTools.h"
 #include "cmake.h"
 
-#include <assert.h>
+#include <cassert>
 #include <vector>
 
 cmCursesCacheEntryComposite::cmCursesCacheEntryComposite(
diff --git a/Source/CursesDialog/cmCursesLongMessageForm.cxx b/Source/CursesDialog/cmCursesLongMessageForm.cxx
index 95026d5474..028cc26546 100644
--- a/Source/CursesDialog/cmCursesLongMessageForm.cxx
+++ b/Source/CursesDialog/cmCursesLongMessageForm.cxx
@@ -7,8 +7,8 @@
 #include "cmCursesStandardIncludes.h"
 #include "cmVersion.h"
 
-#include <stdio.h>
-#include <string.h>
+#include <cstdio>
+#include <cstring>
 
 inline int ctrl(int z)
 {
diff --git a/Source/CursesDialog/cmCursesMainForm.cxx b/Source/CursesDialog/cmCursesMainForm.cxx
index 1b257162a2..5f8a19ed9f 100644
--- a/Source/CursesDialog/cmCursesMainForm.cxx
+++ b/Source/CursesDialog/cmCursesMainForm.cxx
@@ -19,8 +19,8 @@
 #include "cmake.h"
 
 #include <algorithm>
-#include <stdio.h>
-#include <string.h>
+#include <cstdio>
+#include <cstring>
 #include <utility>
 
 inline int ctrl(int z)
diff --git a/Source/CursesDialog/cmCursesMainForm.h b/Source/CursesDialog/cmCursesMainForm.h
index d37997581f..f3194abd69 100644
--- a/Source/CursesDialog/cmCursesMainForm.h
+++ b/Source/CursesDialog/cmCursesMainForm.h
@@ -9,7 +9,7 @@
 #include "cmCursesStandardIncludes.h"
 #include "cmStateTypes.h"
 
-#include <stddef.h>
+#include <cstddef>
 #include <string>
 #include <vector>
 
diff --git a/Source/CursesDialog/cmCursesStringWidget.cxx b/Source/CursesDialog/cmCursesStringWidget.cxx
index 26724e79ec..3fc18587e8 100644
--- a/Source/CursesDialog/cmCursesStringWidget.cxx
+++ b/Source/CursesDialog/cmCursesStringWidget.cxx
@@ -8,8 +8,8 @@
 #include "cmCursesWidget.h"
 #include "cmStateTypes.h"
 
-#include <stdio.h>
-#include <string.h>
+#include <cstdio>
+#include <cstring>
 
 inline int ctrl(int z)
 {
diff --git a/Source/QtDialog/CMakeSetup.cxx b/Source/QtDialog/CMakeSetup.cxx
index 287a482dd7..ad18cfe33c 100644
--- a/Source/QtDialog/CMakeSetup.cxx
+++ b/Source/QtDialog/CMakeSetup.cxx
@@ -229,8 +229,8 @@ int main(int argc, char** argv)
 
 #if defined(Q_OS_MAC)
 #  include "cm_sys_stat.h"
-#  include <errno.h>
-#  include <string.h>
+#  include <cerrno>
+#  include <cstring>
 #  include <unistd.h>
 static bool cmOSXInstall(std::string const& dir, std::string const& tool)
 {
diff --git a/Source/cmAddSubDirectoryCommand.cxx b/Source/cmAddSubDirectoryCommand.cxx
index 17bdc4af9d..c0be308e3a 100644
--- a/Source/cmAddSubDirectoryCommand.cxx
+++ b/Source/cmAddSubDirectoryCommand.cxx
@@ -2,8 +2,8 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmAddSubDirectoryCommand.h"
 
+#include <cstring>
 #include <sstream>
-#include <string.h>
 
 #include "cmExecutionStatus.h"
 #include "cmMakefile.h"
diff --git a/Source/cmAffinity.cxx b/Source/cmAffinity.cxx
index a6d89aaea1..33768a93e7 100644
--- a/Source/cmAffinity.cxx
+++ b/Source/cmAffinity.cxx
@@ -13,7 +13,7 @@
 #    include <pthread.h>
 #    include <sched.h>
 // On some platforms CPU_ZERO needs memset but sched.h forgets string.h
-#    include <string.h> // IWYU pragma: keep
+#    include <cstring> // IWYU pragma: keep
 #    if defined(__FreeBSD__)
 #      include <pthread_np.h>
 #      include <sys/cpuset.h>
diff --git a/Source/cmArchiveWrite.cxx b/Source/cmArchiveWrite.cxx
index a6c25e12e9..c45edaf5c2 100644
--- a/Source/cmArchiveWrite.cxx
+++ b/Source/cmArchiveWrite.cxx
@@ -11,10 +11,10 @@
 #include "cmsys/Encoding.hxx"
 #include "cmsys/FStream.hxx"
 
+#include <cstring>
+#include <ctime>
 #include <iostream>
 #include <sstream>
-#include <string.h>
-#include <time.h>
 
 #ifndef __LA_SSIZE_T
 #  define __LA_SSIZE_T la_ssize_t
diff --git a/Source/cmArchiveWrite.h b/Source/cmArchiveWrite.h
index e90a60346d..e791761cb4 100644
--- a/Source/cmArchiveWrite.h
+++ b/Source/cmArchiveWrite.h
@@ -5,8 +5,8 @@
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
+#include <cstddef>
 #include <iosfwd>
-#include <stddef.h>
 #include <string>
 
 #if defined(CMAKE_BOOTSTRAP)
diff --git a/Source/cmAuxSourceDirectoryCommand.cxx b/Source/cmAuxSourceDirectoryCommand.cxx
index 7bf19d0cf6..111bc41b2a 100644
--- a/Source/cmAuxSourceDirectoryCommand.cxx
+++ b/Source/cmAuxSourceDirectoryCommand.cxx
@@ -4,7 +4,7 @@
 
 #include "cmsys/Directory.hxx"
 #include <algorithm>
-#include <stddef.h>
+#include <cstddef>
 #include <utility>
 
 #include "cmExecutionStatus.h"
diff --git a/Source/cmBase32.h b/Source/cmBase32.h
index c6758d4f3b..d85198dd5f 100644
--- a/Source/cmBase32.h
+++ b/Source/cmBase32.h
@@ -5,7 +5,7 @@
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
-#include <stddef.h>
+#include <cstddef>
 #include <string>
 
 /** \class cmBase32Encoder
diff --git a/Source/cmCMakeHostSystemInformationCommand.cxx b/Source/cmCMakeHostSystemInformationCommand.cxx
index 974b984876..c3f6f406df 100644
--- a/Source/cmCMakeHostSystemInformationCommand.cxx
+++ b/Source/cmCMakeHostSystemInformationCommand.cxx
@@ -2,7 +2,7 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmCMakeHostSystemInformationCommand.h"
 
-#include <stddef.h>
+#include <cstddef>
 
 #include "cmExecutionStatus.h"
 #include "cmMakefile.h"
diff --git a/Source/cmCMakeMinimumRequired.cxx b/Source/cmCMakeMinimumRequired.cxx
index f93c2668a6..1b03873d03 100644
--- a/Source/cmCMakeMinimumRequired.cxx
+++ b/Source/cmCMakeMinimumRequired.cxx
@@ -2,8 +2,8 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmCMakeMinimumRequired.h"
 
+#include <cstdio>
 #include <sstream>
-#include <stdio.h>
 
 #include "cmExecutionStatus.h"
 #include "cmMakefile.h"
diff --git a/Source/cmCPluginAPI.cxx b/Source/cmCPluginAPI.cxx
index f19d99bd70..9c7beca0c2 100644
--- a/Source/cmCPluginAPI.cxx
+++ b/Source/cmCPluginAPI.cxx
@@ -14,7 +14,7 @@
 #include "cmState.h"
 #include "cmVersion.h"
 
-#include <stdlib.h>
+#include <cstdlib>
 
 #ifdef __QNX__
 #  include <malloc.h> /* for malloc/free on QNX */
diff --git a/Source/cmCTest.cxx b/Source/cmCTest.cxx
index cd547706a8..5e17ce8b4a 100644
--- a/Source/cmCTest.cxx
+++ b/Source/cmCTest.cxx
@@ -11,16 +11,16 @@
 #include "cmsys/Process.h"
 #include "cmsys/SystemInformation.hxx"
 #include <algorithm>
+#include <cctype>
 #include <chrono>
-#include <ctype.h>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <ctime>
 #include <iostream>
 #include <map>
 #include <sstream>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
 #include <string>
-#include <time.h>
 #include <utility>
 #include <vector>
 #if defined(_WIN32)
diff --git a/Source/cmCTest.h b/Source/cmCTest.h
index 41dac852e0..9b11653578 100644
--- a/Source/cmCTest.h
+++ b/Source/cmCTest.h
@@ -9,11 +9,11 @@
 #include "cmProcessOutput.h"
 
 #include <chrono>
+#include <ctime>
 #include <map>
 #include <memory>
 #include <sstream>
 #include <string>
-#include <time.h>
 #include <vector>
 
 class cmCTestBuildHandler;
diff --git a/Source/cmCacheManager.cxx b/Source/cmCacheManager.cxx
index e28107fca1..0888a5e9a1 100644
--- a/Source/cmCacheManager.cxx
+++ b/Source/cmCacheManager.cxx
@@ -5,9 +5,9 @@
 #include "cmsys/FStream.hxx"
 #include "cmsys/Glob.hxx"
 #include <algorithm>
+#include <cstdio>
+#include <cstring>
 #include <sstream>
-#include <stdio.h>
-#include <string.h>
 #include <string>
 
 #include "cmGeneratedFileStream.h"
diff --git a/Source/cmCommandArgumentParserHelper.cxx b/Source/cmCommandArgumentParserHelper.cxx
index b368b3a976..e35fba5914 100644
--- a/Source/cmCommandArgumentParserHelper.cxx
+++ b/Source/cmCommandArgumentParserHelper.cxx
@@ -8,9 +8,9 @@
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 
+#include <cstring>
 #include <iostream>
 #include <sstream>
-#include <string.h>
 
 int cmCommandArgument_yyparse(yyscan_t yyscanner);
 //
diff --git a/Source/cmComputeComponentGraph.cxx b/Source/cmComputeComponentGraph.cxx
index 113463f634..655e4ac197 100644
--- a/Source/cmComputeComponentGraph.cxx
+++ b/Source/cmComputeComponentGraph.cxx
@@ -4,7 +4,7 @@
 
 #include <algorithm>
 
-#include <assert.h>
+#include <cassert>
 
 cmComputeComponentGraph::cmComputeComponentGraph(Graph const& input)
   : InputGraph(input)
diff --git a/Source/cmComputeLinkDepends.cxx b/Source/cmComputeLinkDepends.cxx
index 15b0087969..2ee4ca272f 100644
--- a/Source/cmComputeLinkDepends.cxx
+++ b/Source/cmComputeLinkDepends.cxx
@@ -16,11 +16,11 @@
 #include "cmake.h"
 
 #include <algorithm>
-#include <assert.h>
+#include <cassert>
+#include <cstdio>
+#include <cstring>
 #include <iterator>
 #include <sstream>
-#include <stdio.h>
-#include <string.h>
 #include <utility>
 
 #include "cm_memory.hxx"
diff --git a/Source/cmComputeLinkInformation.cxx b/Source/cmComputeLinkInformation.cxx
index ade0f8739e..09dbbb1b36 100644
--- a/Source/cmComputeLinkInformation.cxx
+++ b/Source/cmComputeLinkInformation.cxx
@@ -20,9 +20,9 @@
 #include "cmake.h"
 
 #include <algorithm>
-#include <ctype.h>
+#include <cctype>
+#include <cstring>
 #include <sstream>
-#include <string.h>
 #include <utility>
 
 //#define CM_COMPUTE_LINK_INFO_DEBUG
diff --git a/Source/cmComputeTargetDepends.cxx b/Source/cmComputeTargetDepends.cxx
index de827827a8..239fcdf74d 100644
--- a/Source/cmComputeTargetDepends.cxx
+++ b/Source/cmComputeTargetDepends.cxx
@@ -20,9 +20,9 @@
 #include "cmTargetDepend.h"
 #include "cmake.h"
 
-#include <assert.h>
+#include <cassert>
+#include <cstdio>
 #include <sstream>
-#include <stdio.h>
 #include <utility>
 
 /*
diff --git a/Source/cmConditionEvaluator.cxx b/Source/cmConditionEvaluator.cxx
index 97469be7c5..3ddd8cac0d 100644
--- a/Source/cmConditionEvaluator.cxx
+++ b/Source/cmConditionEvaluator.cxx
@@ -3,11 +3,11 @@
 #include "cmConditionEvaluator.h"
 
 #include "cmsys/RegularExpression.hxx"
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
 #include <functional>
 #include <sstream>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
 #include <utility>
 
 #include "cmAlgorithms.h"
diff --git a/Source/cmCoreTryCompile.cxx b/Source/cmCoreTryCompile.cxx
index 3687056541..12050b383e 100644
--- a/Source/cmCoreTryCompile.cxx
+++ b/Source/cmCoreTryCompile.cxx
@@ -3,10 +3,10 @@
 #include "cmCoreTryCompile.h"
 
 #include "cmsys/Directory.hxx"
+#include <cstdio>
+#include <cstring>
 #include <set>
 #include <sstream>
-#include <stdio.h>
-#include <string.h>
 #include <utility>
 
 #include "cmExportTryCompileFileGenerator.h"
diff --git a/Source/cmCryptoHash.h b/Source/cmCryptoHash.h
index 681f5cc5ee..145ff9198b 100644
--- a/Source/cmCryptoHash.h
+++ b/Source/cmCryptoHash.h
@@ -7,8 +7,8 @@
 
 #include "cm_string_view.hxx"
 
+#include <cstddef>
 #include <memory>
-#include <stddef.h>
 #include <string>
 #include <vector>
 
diff --git a/Source/cmCustomCommandGenerator.cxx b/Source/cmCustomCommandGenerator.cxx
index 82cc03756f..ca2f21087e 100644
--- a/Source/cmCustomCommandGenerator.cxx
+++ b/Source/cmCustomCommandGenerator.cxx
@@ -13,8 +13,8 @@
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 
+#include <cstddef>
 #include <memory>
-#include <stddef.h>
 #include <utility>
 
 cmCustomCommandGenerator::cmCustomCommandGenerator(cmCustomCommand const& cc,
diff --git a/Source/cmDefinitions.cxx b/Source/cmDefinitions.cxx
index e688890fd2..2a117c1494 100644
--- a/Source/cmDefinitions.cxx
+++ b/Source/cmDefinitions.cxx
@@ -4,7 +4,7 @@
 
 #include "cm_string_view.hxx"
 
-#include <assert.h>
+#include <cassert>
 #include <functional>
 #include <unordered_set>
 #include <utility>
diff --git a/Source/cmDependsFortran.cxx b/Source/cmDependsFortran.cxx
index b657ff747a..de919f1906 100644
--- a/Source/cmDependsFortran.cxx
+++ b/Source/cmDependsFortran.cxx
@@ -3,10 +3,10 @@
 #include "cmDependsFortran.h"
 
 #include "cmsys/FStream.hxx"
-#include <assert.h>
+#include <cassert>
+#include <cstdlib>
 #include <iostream>
 #include <map>
-#include <stdlib.h>
 #include <utility>
 
 #include "cmFortranParser.h" /* Interface to parser object.  */
diff --git a/Source/cmDependsJavaParserHelper.cxx b/Source/cmDependsJavaParserHelper.cxx
index 12d875d6f6..63a96d01e5 100644
--- a/Source/cmDependsJavaParserHelper.cxx
+++ b/Source/cmDependsJavaParserHelper.cxx
@@ -7,10 +7,10 @@
 
 #include "cm_string_view.hxx"
 #include "cmsys/FStream.hxx"
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
 #include <iostream>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
 #include <utility>
 
 int cmDependsJava_yyparse(yyscan_t yyscanner);
diff --git a/Source/cmDocumentation.cxx b/Source/cmDocumentation.cxx
index d4628fa7ef..d1f3a83a98 100644
--- a/Source/cmDocumentation.cxx
+++ b/Source/cmDocumentation.cxx
@@ -11,8 +11,8 @@
 #include "cmsys/FStream.hxx"
 #include "cmsys/Glob.hxx"
 #include <algorithm>
-#include <ctype.h>
-#include <string.h>
+#include <cctype>
+#include <cstring>
 #include <utility>
 
 static const char* cmDocumentationStandardOptions[][2] = {
diff --git a/Source/cmDocumentationFormatter.cxx b/Source/cmDocumentationFormatter.cxx
index 3e7f9897eb..be6756a5d8 100644
--- a/Source/cmDocumentationFormatter.cxx
+++ b/Source/cmDocumentationFormatter.cxx
@@ -5,9 +5,9 @@
 #include "cmDocumentationEntry.h"
 #include "cmDocumentationSection.h"
 
+#include <cstring>
 #include <iomanip>
 #include <ostream>
-#include <string.h>
 #include <string>
 #include <vector>
 
diff --git a/Source/cmELF.cxx b/Source/cmELF.cxx
index 90250b6b62..12f996df53 100644
--- a/Source/cmELF.cxx
+++ b/Source/cmELF.cxx
@@ -6,10 +6,10 @@
 #include "cm_kwiml.h"
 #include "cm_memory.hxx"
 #include "cmsys/FStream.hxx"
+#include <cstddef>
 #include <map>
 #include <memory>
 #include <sstream>
-#include <stddef.h>
 #include <utility>
 #include <vector>
 
diff --git a/Source/cmExecProgramCommand.cxx b/Source/cmExecProgramCommand.cxx
index 74e9c55814..207b6fd432 100644
--- a/Source/cmExecProgramCommand.cxx
+++ b/Source/cmExecProgramCommand.cxx
@@ -3,7 +3,7 @@
 #include "cmExecProgramCommand.h"
 
 #include "cmsys/Process.h"
-#include <stdio.h>
+#include <cstdio>
 
 #include "cmExecutionStatus.h"
 #include "cmMakefile.h"
diff --git a/Source/cmExecuteProcessCommand.cxx b/Source/cmExecuteProcessCommand.cxx
index acf2a8334f..12364c8761 100644
--- a/Source/cmExecuteProcessCommand.cxx
+++ b/Source/cmExecuteProcessCommand.cxx
@@ -6,10 +6,10 @@
 #include "cmsys/Process.h"
 
 #include <algorithm>
-#include <ctype.h> /* isspace */
+#include <cctype> /* isspace */
+#include <cstdio>
 #include <iostream>
 #include <memory>
-#include <stdio.h>
 #include <vector>
 
 #include "cmAlgorithms.h"
diff --git a/Source/cmExportFileGenerator.cxx b/Source/cmExportFileGenerator.cxx
index 95458149fb..e588f7bfe8 100644
--- a/Source/cmExportFileGenerator.cxx
+++ b/Source/cmExportFileGenerator.cxx
@@ -19,9 +19,9 @@
 #include "cmTargetExport.h"
 
 #include "cmsys/FStream.hxx"
-#include <assert.h>
+#include <cassert>
+#include <cstring>
 #include <sstream>
-#include <string.h>
 #include <utility>
 
 #include "cm_memory.hxx"
diff --git a/Source/cmExportInstallAndroidMKGenerator.cxx b/Source/cmExportInstallAndroidMKGenerator.cxx
index 1b536c950b..207ea41c35 100644
--- a/Source/cmExportInstallAndroidMKGenerator.cxx
+++ b/Source/cmExportInstallAndroidMKGenerator.cxx
@@ -2,8 +2,8 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmExportInstallAndroidMKGenerator.h"
 
+#include <cstddef>
 #include <ostream>
-#include <stddef.h>
 
 #include "cmExportBuildAndroidMKGenerator.h"
 #include "cmExportSet.h"
diff --git a/Source/cmExtraCodeLiteGenerator.cxx b/Source/cmExtraCodeLiteGenerator.cxx
index 5a01eb249b..e74ad0c789 100644
--- a/Source/cmExtraCodeLiteGenerator.cxx
+++ b/Source/cmExtraCodeLiteGenerator.cxx
@@ -15,10 +15,10 @@
 #include "cmake.h"
 
 #include "cmsys/SystemInformation.hxx"
+#include <cstring>
 #include <map>
 #include <set>
 #include <sstream>
-#include <string.h>
 #include <utility>
 
 cmExtraCodeLiteGenerator::cmExtraCodeLiteGenerator()
diff --git a/Source/cmExtraEclipseCDT4Generator.cxx b/Source/cmExtraEclipseCDT4Generator.cxx
index d39801804b..ca612b5922 100644
--- a/Source/cmExtraEclipseCDT4Generator.cxx
+++ b/Source/cmExtraEclipseCDT4Generator.cxx
@@ -4,10 +4,10 @@
 
 #include "cmsys/RegularExpression.hxx"
 #include <algorithm>
-#include <assert.h>
+#include <cassert>
+#include <cstdio>
 #include <map>
 #include <sstream>
-#include <stdio.h>
 #include <utility>
 
 #include "cmGeneratedFileStream.h"
diff --git a/Source/cmExtraKateGenerator.cxx b/Source/cmExtraKateGenerator.cxx
index 7ac73cfba7..b3d869edfd 100644
--- a/Source/cmExtraKateGenerator.cxx
+++ b/Source/cmExtraKateGenerator.cxx
@@ -12,9 +12,9 @@
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 
+#include <cstring>
 #include <ostream>
 #include <set>
-#include <string.h>
 #include <vector>
 
 cmExtraKateGenerator::cmExtraKateGenerator() = default;
diff --git a/Source/cmExtraSublimeTextGenerator.cxx b/Source/cmExtraSublimeTextGenerator.cxx
index 6ad8609740..f041821936 100644
--- a/Source/cmExtraSublimeTextGenerator.cxx
+++ b/Source/cmExtraSublimeTextGenerator.cxx
@@ -3,9 +3,9 @@
 #include "cmExtraSublimeTextGenerator.h"
 
 #include "cmsys/RegularExpression.hxx"
+#include <cstring>
 #include <set>
 #include <sstream>
-#include <string.h>
 #include <utility>
 
 #include "cmGeneratedFileStream.h"
diff --git a/Source/cmFLTKWrapUICommand.cxx b/Source/cmFLTKWrapUICommand.cxx
index ea9e672f32..afeaf37922 100644
--- a/Source/cmFLTKWrapUICommand.cxx
+++ b/Source/cmFLTKWrapUICommand.cxx
@@ -2,7 +2,7 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmFLTKWrapUICommand.h"
 
-#include <stddef.h>
+#include <cstddef>
 
 #include "cmCustomCommandLines.h"
 #include "cmMakefile.h"
diff --git a/Source/cmFileCommand.cxx b/Source/cmFileCommand.cxx
index e8a7810841..33acd05b1e 100644
--- a/Source/cmFileCommand.cxx
+++ b/Source/cmFileCommand.cxx
@@ -9,14 +9,14 @@
 #include "cmsys/RegularExpression.hxx"
 
 #include <algorithm>
-#include <assert.h>
+#include <cassert>
+#include <cctype>
 #include <cmath>
-#include <ctype.h>
+#include <cstdio>
+#include <cstdlib>
 #include <map>
 #include <set>
 #include <sstream>
-#include <stdio.h>
-#include <stdlib.h>
 #include <utility>
 #include <vector>
 
diff --git a/Source/cmFileCopier.cxx b/Source/cmFileCopier.cxx
index e00e72620d..5b9c85a24a 100644
--- a/Source/cmFileCopier.cxx
+++ b/Source/cmFileCopier.cxx
@@ -16,8 +16,8 @@
 #  include "cmsys/FStream.hxx"
 #endif
 
+#include <cstring>
 #include <sstream>
-#include <string.h>
 
 using namespace cmFSPermissions;
 
diff --git a/Source/cmFileLock.cxx b/Source/cmFileLock.cxx
index 1e472da637..d380798d2e 100644
--- a/Source/cmFileLock.cxx
+++ b/Source/cmFileLock.cxx
@@ -3,7 +3,7 @@
 #include "cmFileLock.h"
 
 #include "cmFileLockResult.h"
-#include <assert.h>
+#include <cassert>
 
 // Common implementation
 
diff --git a/Source/cmFileLockPool.cxx b/Source/cmFileLockPool.cxx
index d700a79c37..8db2db2103 100644
--- a/Source/cmFileLockPool.cxx
+++ b/Source/cmFileLockPool.cxx
@@ -2,7 +2,7 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmFileLockPool.h"
 
-#include <assert.h>
+#include <cassert>
 
 #include "cmAlgorithms.h"
 #include "cmFileLock.h"
diff --git a/Source/cmFileLockResult.cxx b/Source/cmFileLockResult.cxx
index c4779f0648..9d5a6c67af 100644
--- a/Source/cmFileLockResult.cxx
+++ b/Source/cmFileLockResult.cxx
@@ -2,8 +2,8 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmFileLockResult.h"
 
-#include <errno.h>
-#include <string.h>
+#include <cerrno>
+#include <cstring>
 
 #define WINMSG_BUF_LEN (1024)
 cmFileLockResult cmFileLockResult::MakeOk()
diff --git a/Source/cmFileLockUnix.cxx b/Source/cmFileLockUnix.cxx
index 1bf5013add..739382362c 100644
--- a/Source/cmFileLockUnix.cxx
+++ b/Source/cmFileLockUnix.cxx
@@ -3,9 +3,9 @@
 #include "cmFileLock.h"
 
 #include "cmSystemTools.h"
-#include <errno.h> // errno
+#include <cerrno> // errno
+#include <cstdio> // SEEK_SET
 #include <fcntl.h>
-#include <stdio.h> // SEEK_SET
 #include <unistd.h>
 
 cmFileLock::cmFileLock() = default;
diff --git a/Source/cmFileMonitor.cxx b/Source/cmFileMonitor.cxx
index 56ee739b06..7fcced2f17 100644
--- a/Source/cmFileMonitor.cxx
+++ b/Source/cmFileMonitor.cxx
@@ -6,7 +6,7 @@
 #include "cmsys/SystemTools.hxx"
 
 #include <cassert>
-#include <stddef.h>
+#include <cstddef>
 #include <unordered_map>
 #include <utility>
 
diff --git a/Source/cmFilePathChecksum.h b/Source/cmFilePathChecksum.h
index 30881ce90f..b7d5cd24c6 100644
--- a/Source/cmFilePathChecksum.h
+++ b/Source/cmFilePathChecksum.h
@@ -6,7 +6,7 @@
 #include "cmConfigure.h" // IWYU pragma: keep
 
 #include <array>
-#include <stddef.h>
+#include <cstddef>
 #include <string>
 #include <utility>
 
diff --git a/Source/cmFileTime.cxx b/Source/cmFileTime.cxx
index 253457ff24..f92c0ffce4 100644
--- a/Source/cmFileTime.cxx
+++ b/Source/cmFileTime.cxx
@@ -2,8 +2,8 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmFileTime.h"
 
+#include <ctime>
 #include <string>
-#include <time.h>
 
 // Use a platform-specific API to get file times efficiently.
 #if !defined(_WIN32) || defined(__CYGWIN__)
diff --git a/Source/cmFindBase.cxx b/Source/cmFindBase.cxx
index e0daa4f0b7..7d741182d2 100644
--- a/Source/cmFindBase.cxx
+++ b/Source/cmFindBase.cxx
@@ -2,10 +2,10 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmFindBase.h"
 
+#include <cstddef>
 #include <deque>
 #include <iostream>
 #include <map>
-#include <stddef.h>
 
 #include "cmAlgorithms.h"
 #include "cmMakefile.h"
diff --git a/Source/cmFindCommon.cxx b/Source/cmFindCommon.cxx
index 560683830e..badec55a8a 100644
--- a/Source/cmFindCommon.cxx
+++ b/Source/cmFindCommon.cxx
@@ -4,7 +4,7 @@
 
 #include <algorithm>
 #include <array>
-#include <string.h>
+#include <cstring>
 #include <utility>
 
 #include "cmAlgorithms.h"
diff --git a/Source/cmFindLibraryCommand.cxx b/Source/cmFindLibraryCommand.cxx
index 529e5c8761..011e8aaaee 100644
--- a/Source/cmFindLibraryCommand.cxx
+++ b/Source/cmFindLibraryCommand.cxx
@@ -4,9 +4,9 @@
 
 #include "cmsys/RegularExpression.hxx"
 #include <algorithm>
+#include <cstdio>
+#include <cstring>
 #include <set>
-#include <stdio.h>
-#include <string.h>
 #include <utility>
 
 #include "cmGlobalGenerator.h"
diff --git a/Source/cmFindPackageCommand.cxx b/Source/cmFindPackageCommand.cxx
index 8f76030299..8c8cf1397d 100644
--- a/Source/cmFindPackageCommand.cxx
+++ b/Source/cmFindPackageCommand.cxx
@@ -9,13 +9,13 @@
 #include "cmsys/RegularExpression.hxx"
 #include "cmsys/String.h"
 #include <algorithm>
-#include <assert.h>
+#include <cassert>
+#include <cstdio>
+#include <cstring>
 #include <deque>
 #include <functional>
 #include <iterator>
 #include <sstream>
-#include <stdio.h>
-#include <string.h>
 #include <utility>
 
 #include "cm_memory.hxx"
diff --git a/Source/cmForEachCommand.cxx b/Source/cmForEachCommand.cxx
index f0633aadcd..3c39c466cb 100644
--- a/Source/cmForEachCommand.cxx
+++ b/Source/cmForEachCommand.cxx
@@ -2,9 +2,9 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmForEachCommand.h"
 
+#include <cstdio>
+#include <cstdlib>
 #include <sstream>
-#include <stdio.h>
-#include <stdlib.h>
 #include <utility>
 
 #include "cm_memory.hxx"
diff --git a/Source/cmFortranParser.h b/Source/cmFortranParser.h
index 825876c839..6f97b42433 100644
--- a/Source/cmFortranParser.h
+++ b/Source/cmFortranParser.h
@@ -12,7 +12,7 @@
 #  include <vector>
 #endif
 
-#include <stddef.h> /* size_t */
+#include <cstddef> /* size_t */
 
 /* Forward declare parser object type.  */
 using cmFortranParser = struct cmFortranParser_s;
diff --git a/Source/cmFortranParserImpl.cxx b/Source/cmFortranParserImpl.cxx
index ad377deb59..b983b4d968 100644
--- a/Source/cmFortranParserImpl.cxx
+++ b/Source/cmFortranParserImpl.cxx
@@ -5,10 +5,10 @@
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 
-#include <assert.h>
+#include <cassert>
+#include <cstdio>
 #include <set>
 #include <stack>
-#include <stdio.h>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/Source/cmGeneratedFileStream.cxx b/Source/cmGeneratedFileStream.cxx
index 491d96ff66..2af04b691c 100644
--- a/Source/cmGeneratedFileStream.cxx
+++ b/Source/cmGeneratedFileStream.cxx
@@ -2,7 +2,7 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmGeneratedFileStream.h"
 
-#include <stdio.h>
+#include <cstdio>
 
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
diff --git a/Source/cmGeneratorExpression.cxx b/Source/cmGeneratorExpression.cxx
index 7bb6a633ec..f49ed2ccb8 100644
--- a/Source/cmGeneratorExpression.cxx
+++ b/Source/cmGeneratorExpression.cxx
@@ -6,7 +6,6 @@
 #include <memory>
 #include <utility>
 
-#include "assert.h"
 #include "cmAlgorithms.h"
 #include "cmGeneratorExpressionContext.h"
 #include "cmGeneratorExpressionDAGChecker.h"
@@ -15,6 +14,7 @@
 #include "cmGeneratorExpressionParser.h"
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
+#include <cassert>
 
 cmGeneratorExpression::cmGeneratorExpression(cmListFileBacktrace backtrace)
   : Backtrace(std::move(backtrace))
diff --git a/Source/cmGeneratorExpressionDAGChecker.cxx b/Source/cmGeneratorExpressionDAGChecker.cxx
index dda0abc5ab..76f2905245 100644
--- a/Source/cmGeneratorExpressionDAGChecker.cxx
+++ b/Source/cmGeneratorExpressionDAGChecker.cxx
@@ -10,8 +10,8 @@
 #include "cmStringAlgorithms.h"
 #include "cmake.h"
 
+#include <cstring>
 #include <sstream>
-#include <string.h>
 #include <utility>
 
 cmGeneratorExpressionDAGChecker::cmGeneratorExpressionDAGChecker(
diff --git a/Source/cmGeneratorExpressionEvaluator.h b/Source/cmGeneratorExpressionEvaluator.h
index 453015262d..b10bb5bda7 100644
--- a/Source/cmGeneratorExpressionEvaluator.h
+++ b/Source/cmGeneratorExpressionEvaluator.h
@@ -5,7 +5,7 @@
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
-#include <stddef.h>
+#include <cstddef>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/Source/cmGeneratorExpressionLexer.h b/Source/cmGeneratorExpressionLexer.h
index bf24308187..9e0194861b 100644
--- a/Source/cmGeneratorExpressionLexer.h
+++ b/Source/cmGeneratorExpressionLexer.h
@@ -5,7 +5,7 @@
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
-#include <stddef.h>
+#include <cstddef>
 #include <string>
 #include <vector>
 
diff --git a/Source/cmGeneratorExpressionNode.cxx b/Source/cmGeneratorExpressionNode.cxx
index 89b6c1c48b..6cb7a962a6 100644
--- a/Source/cmGeneratorExpressionNode.cxx
+++ b/Source/cmGeneratorExpressionNode.cxx
@@ -30,15 +30,15 @@
 #include "cmsys/String.h"
 
 #include <algorithm>
-#include <assert.h>
-#include <errno.h>
+#include <cassert>
+#include <cerrno>
+#include <cstdlib>
+#include <cstring>
 #include <iterator>
 #include <map>
 #include <memory>
 #include <set>
 #include <sstream>
-#include <stdlib.h>
-#include <string.h>
 #include <utility>
 
 std::string cmGeneratorExpressionNode::EvaluateDependentExpression(
diff --git a/Source/cmGeneratorExpressionParser.cxx b/Source/cmGeneratorExpressionParser.cxx
index ba00b94ff8..a0b685eff4 100644
--- a/Source/cmGeneratorExpressionParser.cxx
+++ b/Source/cmGeneratorExpressionParser.cxx
@@ -5,8 +5,8 @@
 #include "cmAlgorithms.h"
 #include "cmGeneratorExpressionEvaluator.h"
 
-#include <assert.h>
-#include <stddef.h>
+#include <cassert>
+#include <cstddef>
 #include <utility>
 
 cmGeneratorExpressionParser::cmGeneratorExpressionParser(
diff --git a/Source/cmGeneratorTarget.cxx b/Source/cmGeneratorTarget.cxx
index fa04fbb6f4..bc344ab4f5 100644
--- a/Source/cmGeneratorTarget.cxx
+++ b/Source/cmGeneratorTarget.cxx
@@ -4,16 +4,16 @@
 
 #include "cmsys/RegularExpression.hxx"
 #include <algorithm>
-#include <assert.h>
+#include <cassert>
+#include <cerrno>
 #include <cstddef>
-#include <errno.h>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
 #include <iterator>
 #include <memory>
 #include <queue>
 #include <sstream>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
 #include <unordered_set>
 #include <utility>
 
diff --git a/Source/cmGeneratorTarget.h b/Source/cmGeneratorTarget.h
index 9eb2ecf42f..4207d65aa8 100644
--- a/Source/cmGeneratorTarget.h
+++ b/Source/cmGeneratorTarget.h
@@ -10,9 +10,9 @@
 #include "cmPolicies.h"
 #include "cmStateTypes.h"
 
+#include <cstddef>
 #include <map>
 #include <set>
-#include <stddef.h>
 #include <string>
 #include <unordered_map>
 #include <utility>
diff --git a/Source/cmGetPipes.cxx b/Source/cmGetPipes.cxx
index ad323f7ee6..79f90fdf4e 100644
--- a/Source/cmGetPipes.cxx
+++ b/Source/cmGetPipes.cxx
@@ -28,7 +28,7 @@ int cmGetPipes(int* fds)
   return 0;
 }
 #else
-#  include <errno.h>
+#  include <cerrno>
 #  include <unistd.h>
 
 int cmGetPipes(int* fds)
diff --git a/Source/cmGlobalGenerator.cxx b/Source/cmGlobalGenerator.cxx
index 94794249a7..2273c5053a 100644
--- a/Source/cmGlobalGenerator.cxx
+++ b/Source/cmGlobalGenerator.cxx
@@ -5,13 +5,13 @@
 #include "cmsys/Directory.hxx"
 #include "cmsys/FStream.hxx"
 #include <algorithm>
-#include <assert.h>
+#include <cassert>
+#include <cstdio>
+#include <cstdlib>
 #include <cstring>
 #include <initializer_list>
 #include <iterator>
 #include <sstream>
-#include <stdio.h>
-#include <stdlib.h>
 
 #if defined(_WIN32) && !defined(__CYGWIN__)
 #  include <windows.h>
diff --git a/Source/cmGlobalGhsMultiGenerator.cxx b/Source/cmGlobalGhsMultiGenerator.cxx
index 0b45f4bf47..236554f8d2 100644
--- a/Source/cmGlobalGhsMultiGenerator.cxx
+++ b/Source/cmGlobalGhsMultiGenerator.cxx
@@ -18,9 +18,9 @@
 #include "cmake.h"
 
 #include <algorithm>
+#include <cstring>
 #include <map>
 #include <ostream>
-#include <string.h>
 #include <utility>
 
 const char* cmGlobalGhsMultiGenerator::FILE_EXTENSION = ".gpj";
diff --git a/Source/cmGlobalNinjaGenerator.cxx b/Source/cmGlobalNinjaGenerator.cxx
index 062eccb199..9ce6324749 100644
--- a/Source/cmGlobalNinjaGenerator.cxx
+++ b/Source/cmGlobalNinjaGenerator.cxx
@@ -7,10 +7,10 @@
 #include "cm_jsoncpp_writer.h"
 #include "cmsys/FStream.hxx"
 #include <algorithm>
-#include <ctype.h>
+#include <cctype>
+#include <cstdio>
 #include <iterator>
 #include <sstream>
-#include <stdio.h>
 
 #include "cm_memory.hxx"
 
diff --git a/Source/cmGlobalUnixMakefileGenerator3.h b/Source/cmGlobalUnixMakefileGenerator3.h
index 264de54ee1..6a39509ae2 100644
--- a/Source/cmGlobalUnixMakefileGenerator3.h
+++ b/Source/cmGlobalUnixMakefileGenerator3.h
@@ -5,10 +5,10 @@
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
+#include <cstddef>
 #include <iosfwd>
 #include <map>
 #include <set>
-#include <stddef.h>
 #include <string>
 #include <vector>
 
diff --git a/Source/cmGlobalXCodeGenerator.cxx b/Source/cmGlobalXCodeGenerator.cxx
index af5d2796de..de04e841dd 100644
--- a/Source/cmGlobalXCodeGenerator.cxx
+++ b/Source/cmGlobalXCodeGenerator.cxx
@@ -3,11 +3,11 @@
 #include "cmGlobalXCodeGenerator.h"
 
 #include "cmsys/RegularExpression.hxx"
-#include <assert.h>
+#include <cassert>
+#include <cstdio>
+#include <cstring>
 #include <iomanip>
 #include <sstream>
-#include <stdio.h>
-#include <string.h>
 
 #include "cm_memory.hxx"
 
diff --git a/Source/cmHexFileConverter.cxx b/Source/cmHexFileConverter.cxx
index 190f2e3054..2fa4b55058 100644
--- a/Source/cmHexFileConverter.cxx
+++ b/Source/cmHexFileConverter.cxx
@@ -2,9 +2,9 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmHexFileConverter.h"
 
-#include <ctype.h>
-#include <stdio.h>
-#include <string.h>
+#include <cctype>
+#include <cstdio>
+#include <cstring>
 
 #include "cmSystemTools.h"
 
diff --git a/Source/cmInstallCommand.cxx b/Source/cmInstallCommand.cxx
index 9a78c49156..9b931f76e5 100644
--- a/Source/cmInstallCommand.cxx
+++ b/Source/cmInstallCommand.cxx
@@ -4,9 +4,9 @@
 
 #include "cm_static_string_view.hxx"
 #include "cmsys/Glob.hxx"
+#include <cstddef>
 #include <set>
 #include <sstream>
-#include <stddef.h>
 #include <utility>
 
 #include "cmArgumentParser.h"
diff --git a/Source/cmInstallExportGenerator.h b/Source/cmInstallExportGenerator.h
index e680066166..3b9268a29f 100644
--- a/Source/cmInstallExportGenerator.h
+++ b/Source/cmInstallExportGenerator.h
@@ -8,8 +8,8 @@
 #include "cmInstallGenerator.h"
 #include "cmScriptGenerator.h"
 
+#include <cstddef>
 #include <iosfwd>
-#include <stddef.h>
 #include <string>
 #include <vector>
 
diff --git a/Source/cmInstallTargetGenerator.cxx b/Source/cmInstallTargetGenerator.cxx
index 7bbef35662..90b0e1d9a7 100644
--- a/Source/cmInstallTargetGenerator.cxx
+++ b/Source/cmInstallTargetGenerator.cxx
@@ -2,7 +2,7 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmInstallTargetGenerator.h"
 
-#include <assert.h>
+#include <cassert>
 #include <map>
 #include <memory>
 #include <set>
diff --git a/Source/cmLinkedTree.h b/Source/cmLinkedTree.h
index 8b91162192..c7453eac92 100644
--- a/Source/cmLinkedTree.h
+++ b/Source/cmLinkedTree.h
@@ -5,7 +5,7 @@
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
-#include <assert.h>
+#include <cassert>
 #include <vector>
 
 /**
diff --git a/Source/cmListCommand.cxx b/Source/cmListCommand.cxx
index b35dc6f337..9487e3b5ec 100644
--- a/Source/cmListCommand.cxx
+++ b/Source/cmListCommand.cxx
@@ -4,15 +4,15 @@
 
 #include "cmsys/RegularExpression.hxx"
 #include <algorithm>
-#include <assert.h>
+#include <cassert>
 #include <cstddef>
+#include <cstdio>
+#include <cstdlib> // required for atoi
 #include <functional>
 #include <iterator>
 #include <set>
 #include <sstream>
 #include <stdexcept>
-#include <stdio.h>
-#include <stdlib.h> // required for atoi
 #include <utility>
 #include <vector>
 
diff --git a/Source/cmListFileCache.cxx b/Source/cmListFileCache.cxx
index 349d5e9542..ab53df6e4e 100644
--- a/Source/cmListFileCache.cxx
+++ b/Source/cmListFileCache.cxx
@@ -10,7 +10,7 @@
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 
-#include <assert.h>
+#include <cassert>
 #include <memory>
 #include <sstream>
 #include <utility>
diff --git a/Source/cmListFileCache.h b/Source/cmListFileCache.h
index 5de1a74506..9cae8277b2 100644
--- a/Source/cmListFileCache.h
+++ b/Source/cmListFileCache.h
@@ -5,9 +5,9 @@
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
+#include <cstddef>
 #include <iosfwd>
 #include <memory>
-#include <stddef.h>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/Source/cmLoadCommandCommand.cxx b/Source/cmLoadCommandCommand.cxx
index f650eb1016..66fdada3d7 100644
--- a/Source/cmLoadCommandCommand.cxx
+++ b/Source/cmLoadCommandCommand.cxx
@@ -2,12 +2,12 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmLoadCommandCommand.h"
 
-#include <signal.h>
+#include <csignal>
 
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
 #include <sstream>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
 #include <utility>
 
 #include "cm_memory.hxx"
diff --git a/Source/cmLocalGenerator.cxx b/Source/cmLocalGenerator.cxx
index 51eb78ce3d..5bbb83cdc2 100644
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -38,15 +38,15 @@
 #endif
 
 #include <algorithm>
-#include <assert.h>
+#include <cassert>
+#include <cstdio>
 #include <cstdlib>
+#include <cstring>
 #include <functional>
 #include <initializer_list>
 #include <iterator>
 #include <memory>
 #include <sstream>
-#include <stdio.h>
-#include <string.h>
 #include <unordered_set>
 #include <utility>
 #include <vector>
diff --git a/Source/cmLocalNinjaGenerator.cxx b/Source/cmLocalNinjaGenerator.cxx
index 1284d4dba1..0fe385f554 100644
--- a/Source/cmLocalNinjaGenerator.cxx
+++ b/Source/cmLocalNinjaGenerator.cxx
@@ -3,11 +3,11 @@
 #include "cmLocalNinjaGenerator.h"
 
 #include <algorithm>
-#include <assert.h>
+#include <cassert>
+#include <cstdio>
 #include <iterator>
 #include <memory>
 #include <sstream>
-#include <stdio.h>
 #include <utility>
 
 #include "cmCryptoHash.h"
diff --git a/Source/cmLocalUnixMakefileGenerator3.cxx b/Source/cmLocalUnixMakefileGenerator3.cxx
index 8248608347..f80695dfc2 100644
--- a/Source/cmLocalUnixMakefileGenerator3.cxx
+++ b/Source/cmLocalUnixMakefileGenerator3.cxx
@@ -5,8 +5,8 @@
 #include "cmsys/FStream.hxx"
 #include "cmsys/Terminal.h"
 #include <algorithm>
+#include <cstdio>
 #include <sstream>
-#include <stdio.h>
 #include <utility>
 
 #include "cm_memory.hxx"
diff --git a/Source/cmLocale.h b/Source/cmLocale.h
index 3580ec8125..c44a42db7f 100644
--- a/Source/cmLocale.h
+++ b/Source/cmLocale.h
@@ -5,7 +5,7 @@
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
-#include <locale.h>
+#include <clocale>
 #include <string>
 
 class cmLocaleRAII
diff --git a/Source/cmMacroCommand.cxx b/Source/cmMacroCommand.cxx
index ef6a70500f..af97761fcd 100644
--- a/Source/cmMacroCommand.cxx
+++ b/Source/cmMacroCommand.cxx
@@ -2,7 +2,7 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmMacroCommand.h"
 
-#include <stdio.h>
+#include <cstdio>
 #include <utility>
 
 #include "cm_memory.hxx"
diff --git a/Source/cmMakefile.cxx b/Source/cmMakefile.cxx
index 16cc453fdd..d73a285baa 100644
--- a/Source/cmMakefile.cxx
+++ b/Source/cmMakefile.cxx
@@ -5,14 +5,14 @@
 #include "cmsys/FStream.hxx"
 #include "cmsys/RegularExpression.hxx"
 #include <algorithm>
-#include <assert.h>
+#include <cassert>
+#include <cctype>
+#include <cstdio>
+#include <cstdlib>
 #include <cstring>
-#include <ctype.h>
 #include <iterator>
 #include <memory>
 #include <sstream>
-#include <stdio.h>
-#include <stdlib.h>
 #include <utility>
 
 #include "cmAlgorithms.h"
diff --git a/Source/cmMakefile.h b/Source/cmMakefile.h
index 52464d641e..252b85501e 100644
--- a/Source/cmMakefile.h
+++ b/Source/cmMakefile.h
@@ -6,13 +6,13 @@
 #include "cmConfigure.h" // IWYU pragma: keep
 
 #include "cmsys/RegularExpression.hxx"
+#include <cstddef>
 #include <deque>
 #include <functional>
 #include <map>
 #include <memory>
 #include <set>
 #include <stack>
-#include <stddef.h>
 #include <string>
 #include <unordered_map>
 #include <vector>
diff --git a/Source/cmMakefileLibraryTargetGenerator.cxx b/Source/cmMakefileLibraryTargetGenerator.cxx
index 6d71a6df0d..b37a933caf 100644
--- a/Source/cmMakefileLibraryTargetGenerator.cxx
+++ b/Source/cmMakefileLibraryTargetGenerator.cxx
@@ -2,9 +2,9 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmMakefileLibraryTargetGenerator.h"
 
+#include <cstddef>
 #include <set>
 #include <sstream>
-#include <stddef.h>
 #include <utility>
 #include <vector>
 
diff --git a/Source/cmMakefileTargetGenerator.cxx b/Source/cmMakefileTargetGenerator.cxx
index 1f6986b58e..477badd6de 100644
--- a/Source/cmMakefileTargetGenerator.cxx
+++ b/Source/cmMakefileTargetGenerator.cxx
@@ -2,9 +2,9 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmMakefileTargetGenerator.h"
 
+#include <cstdio>
 #include <memory>
 #include <sstream>
-#include <stdio.h>
 #include <utility>
 
 #include "cmAlgorithms.h"
diff --git a/Source/cmMathCommand.cxx b/Source/cmMathCommand.cxx
index 83c22aaf20..4ea36386ee 100644
--- a/Source/cmMathCommand.cxx
+++ b/Source/cmMathCommand.cxx
@@ -8,7 +8,7 @@
 #include "cmMessageType.h"
 #include "cm_kwiml.h"
 
-#include <stdio.h>
+#include <cstdio>
 
 namespace {
 bool HandleExprCommand(std::vector<std::string> const& args,
diff --git a/Source/cmNewLineStyle.cxx b/Source/cmNewLineStyle.cxx
index 1ff741e4ff..a121332b2c 100644
--- a/Source/cmNewLineStyle.cxx
+++ b/Source/cmNewLineStyle.cxx
@@ -2,7 +2,7 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmNewLineStyle.h"
 
-#include <stddef.h>
+#include <cstddef>
 
 cmNewLineStyle::cmNewLineStyle() = default;
 
diff --git a/Source/cmNinjaNormalTargetGenerator.cxx b/Source/cmNinjaNormalTargetGenerator.cxx
index bc2506eb8a..97742c1b19 100644
--- a/Source/cmNinjaNormalTargetGenerator.cxx
+++ b/Source/cmNinjaNormalTargetGenerator.cxx
@@ -3,7 +3,7 @@
 #include "cmNinjaNormalTargetGenerator.h"
 
 #include <algorithm>
-#include <assert.h>
+#include <cassert>
 #include <iterator>
 #include <map>
 #include <set>
diff --git a/Source/cmNinjaTargetGenerator.cxx b/Source/cmNinjaTargetGenerator.cxx
index 90b59e7635..37e9e0e90a 100644
--- a/Source/cmNinjaTargetGenerator.cxx
+++ b/Source/cmNinjaTargetGenerator.cxx
@@ -5,7 +5,7 @@
 #include "cm_jsoncpp_value.h"
 #include "cm_jsoncpp_writer.h"
 #include <algorithm>
-#include <assert.h>
+#include <cassert>
 #include <iterator>
 #include <map>
 #include <ostream>
diff --git a/Source/cmOrderDirectories.cxx b/Source/cmOrderDirectories.cxx
index c8cac3bc03..e1267ec484 100644
--- a/Source/cmOrderDirectories.cxx
+++ b/Source/cmOrderDirectories.cxx
@@ -11,7 +11,7 @@
 #include "cmake.h"
 
 #include <algorithm>
-#include <assert.h>
+#include <cassert>
 #include <functional>
 #include <sstream>
 #include <vector>
diff --git a/Source/cmOutputConverter.cxx b/Source/cmOutputConverter.cxx
index bf516e3d13..e602a6d0ab 100644
--- a/Source/cmOutputConverter.cxx
+++ b/Source/cmOutputConverter.cxx
@@ -3,8 +3,8 @@
 #include "cmOutputConverter.h"
 
 #include <algorithm>
-#include <assert.h>
-#include <ctype.h>
+#include <cassert>
+#include <cctype>
 #include <set>
 #include <vector>
 
diff --git a/Source/cmOutputRequiredFilesCommand.cxx b/Source/cmOutputRequiredFilesCommand.cxx
index 2f4e003856..d9a433d1e8 100644
--- a/Source/cmOutputRequiredFilesCommand.cxx
+++ b/Source/cmOutputRequiredFilesCommand.cxx
@@ -4,9 +4,9 @@
 
 #include "cmsys/FStream.hxx"
 #include "cmsys/RegularExpression.hxx"
+#include <cstdio>
 #include <map>
 #include <set>
-#include <stdio.h>
 #include <utility>
 
 #include "cmAlgorithms.h"
diff --git a/Source/cmPolicies.cxx b/Source/cmPolicies.cxx
index d33cd32804..c8bc56de05 100644
--- a/Source/cmPolicies.cxx
+++ b/Source/cmPolicies.cxx
@@ -8,11 +8,11 @@
 #include "cmSystemTools.h"
 #include "cmVersion.h"
 
-#include <assert.h>
-#include <ctype.h>
+#include <cassert>
+#include <cctype>
+#include <cstdio>
+#include <cstring>
 #include <sstream>
-#include <stdio.h>
-#include <string.h>
 #include <vector>
 
 static bool stringToId(const char* input, cmPolicies::PolicyID& pid)
diff --git a/Source/cmProcessOutput.h b/Source/cmProcessOutput.h
index 400354c842..3db47a4b49 100644
--- a/Source/cmProcessOutput.h
+++ b/Source/cmProcessOutput.h
@@ -5,7 +5,7 @@
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
-#include <stddef.h>
+#include <cstddef>
 #include <string>
 #include <vector>
 
diff --git a/Source/cmProcessTools.h b/Source/cmProcessTools.h
index c205a8ff54..7d97e366a5 100644
--- a/Source/cmProcessTools.h
+++ b/Source/cmProcessTools.h
@@ -6,8 +6,8 @@
 #include "cmConfigure.h" // IWYU pragma: keep
 #include "cmProcessOutput.h"
 
+#include <cstring>
 #include <iosfwd>
-#include <string.h>
 #include <string>
 
 /** \class cmProcessTools
diff --git a/Source/cmRST.cxx b/Source/cmRST.cxx
index aa394e5dae..edbb3dee46 100644
--- a/Source/cmRST.cxx
+++ b/Source/cmRST.cxx
@@ -10,9 +10,9 @@
 
 #include "cmsys/FStream.hxx"
 #include <algorithm>
-#include <ctype.h>
+#include <cctype>
+#include <cstddef>
 #include <iterator>
-#include <stddef.h>
 #include <utility>
 
 cmRST::cmRST(std::ostream& os, std::string docroot)
diff --git a/Source/cmRulePlaceholderExpander.cxx b/Source/cmRulePlaceholderExpander.cxx
index 6c954a6255..0a1d109d56 100644
--- a/Source/cmRulePlaceholderExpander.cxx
+++ b/Source/cmRulePlaceholderExpander.cxx
@@ -2,8 +2,8 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmRulePlaceholderExpander.h"
 
-#include <ctype.h>
-#include <string.h>
+#include <cctype>
+#include <cstring>
 #include <utility>
 
 #include "cmOutputConverter.h"
diff --git a/Source/cmSourceFileLocation.cxx b/Source/cmSourceFileLocation.cxx
index 0e8d09d14b..bd75c14a1a 100644
--- a/Source/cmSourceFileLocation.cxx
+++ b/Source/cmSourceFileLocation.cxx
@@ -9,7 +9,7 @@
 #include "cmSystemTools.h"
 #include "cmake.h"
 
-#include <assert.h>
+#include <cassert>
 
 cmSourceFileLocation::cmSourceFileLocation() = default;
 
diff --git a/Source/cmSourceGroupCommand.cxx b/Source/cmSourceGroupCommand.cxx
index c239a1f450..3be7fec386 100644
--- a/Source/cmSourceGroupCommand.cxx
+++ b/Source/cmSourceGroupCommand.cxx
@@ -2,8 +2,8 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmSourceGroupCommand.h"
 
+#include <cstddef>
 #include <set>
-#include <stddef.h>
 #include <utility>
 
 #include "cmAlgorithms.h"
diff --git a/Source/cmState.cxx b/Source/cmState.cxx
index 751eb77062..7463bf8d80 100644
--- a/Source/cmState.cxx
+++ b/Source/cmState.cxx
@@ -4,9 +4,9 @@
 
 #include "cmsys/RegularExpression.hxx"
 #include <algorithm>
-#include <assert.h>
-#include <stdlib.h>
-#include <string.h>
+#include <cassert>
+#include <cstdlib>
+#include <cstring>
 #include <utility>
 
 #include "cm_memory.hxx"
diff --git a/Source/cmStateDirectory.cxx b/Source/cmStateDirectory.cxx
index c14bf4acd8..ede00a0219 100644
--- a/Source/cmStateDirectory.cxx
+++ b/Source/cmStateDirectory.cxx
@@ -4,7 +4,7 @@
 #include "cmStateDirectory.h"
 
 #include <algorithm>
-#include <assert.h>
+#include <cassert>
 #include <iterator>
 #include <vector>
 
diff --git a/Source/cmStateSnapshot.cxx b/Source/cmStateSnapshot.cxx
index b3e33eae59..28d5170bf6 100644
--- a/Source/cmStateSnapshot.cxx
+++ b/Source/cmStateSnapshot.cxx
@@ -4,7 +4,7 @@
 #include "cmStateSnapshot.h"
 
 #include <algorithm>
-#include <assert.h>
+#include <cassert>
 #include <iterator>
 #include <string>
 
diff --git a/Source/cmStringAlgorithms.cxx b/Source/cmStringAlgorithms.cxx
index 131a01ecf5..bb6dcd7342 100644
--- a/Source/cmStringAlgorithms.cxx
+++ b/Source/cmStringAlgorithms.cxx
@@ -3,10 +3,10 @@
 #include "cmStringAlgorithms.h"
 
 #include <algorithm>
+#include <cerrno>
 #include <cstddef>
 #include <cstdio>
-#include <errno.h>
-#include <stdlib.h>
+#include <cstdlib>
 
 std::string cmTrimWhitespace(cm::string_view str)
 {
diff --git a/Source/cmStringAlgorithms.h b/Source/cmStringAlgorithms.h
index 7f442d8489..cb6b8ba9ff 100644
--- a/Source/cmStringAlgorithms.h
+++ b/Source/cmStringAlgorithms.h
@@ -8,9 +8,9 @@
 #include "cmRange.h"
 #include "cm_string_view.hxx"
 #include <cctype>
+#include <cstring>
 #include <initializer_list>
 #include <sstream>
-#include <string.h>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/Source/cmStringCommand.cxx b/Source/cmStringCommand.cxx
index 9a2de9d7be..ab670cac7e 100644
--- a/Source/cmStringCommand.cxx
+++ b/Source/cmStringCommand.cxx
@@ -6,12 +6,12 @@
 
 #include "cmsys/RegularExpression.hxx"
 #include <algorithm>
-#include <ctype.h>
+#include <cctype>
+#include <cstdio>
+#include <cstdlib>
 #include <iterator>
 #include <memory>
 #include <sstream>
-#include <stdio.h>
-#include <stdlib.h>
 
 #include "cm_static_string_view.hxx"
 
diff --git a/Source/cmSystemTools.cxx b/Source/cmSystemTools.cxx
index 86af683f9e..62a8d8f952 100644
--- a/Source/cmSystemTools.cxx
+++ b/Source/cmSystemTools.cxx
@@ -40,16 +40,16 @@
 #include "cmsys/System.h"
 #include "cmsys/Terminal.h"
 #include <algorithm>
-#include <assert.h>
-#include <ctype.h>
-#include <errno.h>
+#include <cassert>
+#include <cctype>
+#include <cerrno>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <ctime>
 #include <fcntl.h>
 #include <iostream>
 #include <sstream>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <time.h>
 #include <utility>
 #include <vector>
 
diff --git a/Source/cmSystemTools.h b/Source/cmSystemTools.h
index 8ca4939ee4..e7eef338b6 100644
--- a/Source/cmSystemTools.h
+++ b/Source/cmSystemTools.h
@@ -11,8 +11,8 @@
 #include "cm_string_view.hxx"
 #include "cmsys/Process.h"
 #include "cmsys/SystemTools.hxx" // IWYU pragma: export
+#include <cstddef>
 #include <functional>
-#include <stddef.h>
 #include <string>
 #include <vector>
 
diff --git a/Source/cmTarget.cxx b/Source/cmTarget.cxx
index 2420810f08..6637e32dc7 100644
--- a/Source/cmTarget.cxx
+++ b/Source/cmTarget.cxx
@@ -4,12 +4,12 @@
 
 #include "cmsys/RegularExpression.hxx"
 #include <algorithm>
-#include <assert.h>
+#include <cassert>
+#include <cstring>
 #include <initializer_list>
 #include <iterator>
 #include <set>
 #include <sstream>
-#include <string.h>
 #include <unordered_set>
 
 #include "cm_memory.hxx"
diff --git a/Source/cmTargetLinkLibrariesCommand.cxx b/Source/cmTargetLinkLibrariesCommand.cxx
index 4fbec903ff..237d90c901 100644
--- a/Source/cmTargetLinkLibrariesCommand.cxx
+++ b/Source/cmTargetLinkLibrariesCommand.cxx
@@ -2,8 +2,8 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmTargetLinkLibrariesCommand.h"
 
+#include <cstring>
 #include <sstream>
-#include <string.h>
 
 #include "cmGeneratorExpression.h"
 #include "cmGlobalGenerator.h"
diff --git a/Source/cmTimestamp.cxx b/Source/cmTimestamp.cxx
index a9be729e77..390fd16b0b 100644
--- a/Source/cmTimestamp.cxx
+++ b/Source/cmTimestamp.cxx
@@ -2,9 +2,9 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmTimestamp.h"
 
+#include <cstdlib>
 #include <cstring>
 #include <sstream>
-#include <stdlib.h>
 
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
diff --git a/Source/cmTimestamp.h b/Source/cmTimestamp.h
index d5fbdfd671..40338f8b24 100644
--- a/Source/cmTimestamp.h
+++ b/Source/cmTimestamp.h
@@ -5,8 +5,8 @@
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
+#include <ctime>
 #include <string>
-#include <time.h>
 
 /** \class cmTimestamp
  * \brief Utility class to generate string representation of a timestamp
diff --git a/Source/cmTryRunCommand.cxx b/Source/cmTryRunCommand.cxx
index 24d0f0f20c..73354ec83a 100644
--- a/Source/cmTryRunCommand.cxx
+++ b/Source/cmTryRunCommand.cxx
@@ -3,7 +3,7 @@
 #include "cmTryRunCommand.h"
 
 #include "cmsys/FStream.hxx"
-#include <stdio.h>
+#include <cstdio>
 
 #include "cmDuration.h"
 #include "cmMakefile.h"
diff --git a/Source/cmUVHandlePtr.cxx b/Source/cmUVHandlePtr.cxx
index 97c27cbaaf..23dabb770b 100644
--- a/Source/cmUVHandlePtr.cxx
+++ b/Source/cmUVHandlePtr.cxx
@@ -3,9 +3,9 @@
 #define cmUVHandlePtr_cxx
 #include "cmUVHandlePtr.h"
 
-#include <assert.h>
+#include <cassert>
+#include <cstdlib>
 #include <mutex>
-#include <stdlib.h>
 
 #include "cm_uv.h"
 
diff --git a/Source/cmUVProcessChain.cxx b/Source/cmUVProcessChain.cxx
index 56d6c09b04..2c37a642cc 100644
--- a/Source/cmUVProcessChain.cxx
+++ b/Source/cmUVProcessChain.cxx
@@ -7,7 +7,7 @@
 #include "cmUVStreambuf.h"
 #include "cm_uv.h"
 
-#include <assert.h>
+#include <cassert>
 
 #include <istream> // IWYU pragma: keep
 #include <iterator>
diff --git a/Source/cmUVProcessChain.h b/Source/cmUVProcessChain.h
index 76a9c40cb0..8a19bc3372 100644
--- a/Source/cmUVProcessChain.h
+++ b/Source/cmUVProcessChain.h
@@ -7,13 +7,12 @@
 
 #include <array>
 #include <cstddef>
+#include <cstdint>
 #include <iosfwd>
 #include <memory>
 #include <string>
 #include <vector>
 
-#include <stdint.h>
-
 class cmUVProcessChain;
 
 class cmUVProcessChainBuilder
diff --git a/Source/cmUtilitySourceCommand.cxx b/Source/cmUtilitySourceCommand.cxx
index 6b3590f3b5..a43165cce7 100644
--- a/Source/cmUtilitySourceCommand.cxx
+++ b/Source/cmUtilitySourceCommand.cxx
@@ -2,7 +2,7 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmUtilitySourceCommand.h"
 
-#include <string.h>
+#include <cstring>
 
 #include "cmExecutionStatus.h"
 #include "cmMakefile.h"
diff --git a/Source/cmUuid.cxx b/Source/cmUuid.cxx
index 91c8af3256..f0f2c51203 100644
--- a/Source/cmUuid.cxx
+++ b/Source/cmUuid.cxx
@@ -5,7 +5,7 @@
 #include "cmCryptoHash.h"
 
 #include <array>
-#include <string.h>
+#include <cstring>
 
 static const std::array<int, 5> kUuidGroups = { { 4, 2, 2, 2, 6 } };
 
diff --git a/Source/cmWorkerPool.cxx b/Source/cmWorkerPool.cxx
index 2e4d00bd31..5ac81df67d 100644
--- a/Source/cmWorkerPool.cxx
+++ b/Source/cmWorkerPool.cxx
@@ -11,10 +11,10 @@
 #include <algorithm>
 #include <array>
 #include <condition_variable>
+#include <cstddef>
 #include <deque>
 #include <functional>
 #include <mutex>
-#include <stddef.h>
 #include <thread>
 
 #include "cm_memory.hxx"
diff --git a/Source/cmWorkerPool.h b/Source/cmWorkerPool.h
index b541ce31b4..bf072990e4 100644
--- a/Source/cmWorkerPool.h
+++ b/Source/cmWorkerPool.h
@@ -5,7 +5,7 @@
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
-#include <stdint.h>
+#include <cstdint>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/Source/cmXMLParser.cxx b/Source/cmXMLParser.cxx
index 4c6c35acc5..1f69032825 100644
--- a/Source/cmXMLParser.cxx
+++ b/Source/cmXMLParser.cxx
@@ -4,10 +4,10 @@
 
 #include "cm_expat.h"
 #include "cmsys/FStream.hxx"
-#include <ctype.h>
+#include <cctype>
+#include <cstring>
 #include <iostream>
 #include <sstream>
-#include <string.h>
 
 cmXMLParser::cmXMLParser()
 {
diff --git a/Source/cmXMLSafe.cxx b/Source/cmXMLSafe.cxx
index d9bdc023b0..7c3b30647b 100644
--- a/Source/cmXMLSafe.cxx
+++ b/Source/cmXMLSafe.cxx
@@ -4,9 +4,9 @@
 
 #include "cm_utf8.h"
 
+#include <cstdio>
+#include <cstring>
 #include <sstream>
-#include <stdio.h>
-#include <string.h>
 
 cmXMLSafe::cmXMLSafe(const char* s)
   : Data(s)
diff --git a/Source/cm_codecvt.hxx b/Source/cm_codecvt.hxx
index 20605846a9..b2cb9e6a35 100644
--- a/Source/cm_codecvt.hxx
+++ b/Source/cm_codecvt.hxx
@@ -5,8 +5,8 @@
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
+#include <cwchar>
 #include <locale>
-#include <wchar.h>
 
 class codecvt : public std::codecvt<char, char, mbstate_t>
 {
diff --git a/Source/cm_get_date.h b/Source/cm_get_date.h
index 6acf8dea3b..38a690ee05 100644
--- a/Source/cm_get_date.h
+++ b/Source/cm_get_date.h
@@ -3,7 +3,7 @@
 #ifndef cm_get_date_h
 #define cm_get_date_h
 
-#include <time.h>
+#include <time.h> /* NOLINT(modernize-deprecated-headers) */
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/Source/cmake.cxx b/Source/cmake.cxx
index 170e09b784..9a66805994 100644
--- a/Source/cmake.cxx
+++ b/Source/cmake.cxx
@@ -105,12 +105,12 @@
 #include "cmsys/Glob.hxx"
 #include "cmsys/RegularExpression.hxx"
 #include <algorithm>
+#include <cstdio>
+#include <cstdlib>
 #include <cstring>
 #include <initializer_list>
 #include <iostream>
 #include <sstream>
-#include <stdio.h>
-#include <stdlib.h>
 #include <utility>
 
 namespace {
diff --git a/Source/cmakemain.cxx b/Source/cmakemain.cxx
index 2b51a2a546..252c6d6d0b 100644
--- a/Source/cmakemain.cxx
+++ b/Source/cmakemain.cxx
@@ -25,10 +25,10 @@
 #endif
 
 #include <cassert>
+#include <cctype>
 #include <climits>
-#include <ctype.h>
+#include <cstring>
 #include <iostream>
-#include <string.h>
 #include <string>
 #include <vector>
 
diff --git a/Source/cmcmd.cxx b/Source/cmcmd.cxx
index ba2ba338a5..211fd4c723 100644
--- a/Source/cmcmd.cxx
+++ b/Source/cmcmd.cxx
@@ -39,13 +39,13 @@
 #include "cmsys/Process.h"
 #include "cmsys/Terminal.h"
 #include <array>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <ctime>
 #include <iostream>
 #include <memory>
 #include <sstream>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <time.h>
 #include <utility>
 
 class cmConnection;
diff --git a/Source/ctest.cxx b/Source/ctest.cxx
index a69ba1532a..7be6746295 100644
--- a/Source/ctest.cxx
+++ b/Source/ctest.cxx
@@ -11,8 +11,8 @@
 #if defined(_WIN32) && !defined(CMAKE_BOOTSTRAP)
 #  include "cmsys/ConsoleBuf.hxx"
 #endif
+#include <cstring>
 #include <iostream>
-#include <string.h>
 #include <string>
 #include <vector>
 
diff --git a/Tests/CMakeLib/run_compile_commands.cxx b/Tests/CMakeLib/run_compile_commands.cxx
index 010e17a27d..4a79c80411 100644
--- a/Tests/CMakeLib/run_compile_commands.cxx
+++ b/Tests/CMakeLib/run_compile_commands.cxx
@@ -1,9 +1,9 @@
 #include "cmConfigure.h" // IWYU pragma: keep
 
 #include "cmsys/FStream.hxx"
+#include <cstdlib>
 #include <iostream>
 #include <map>
-#include <stdlib.h>
 #include <string>
 #include <utility>
 #include <vector>