diff --git a/.gitattributes b/.gitattributes
index 9b127bc2..451b824d 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -3,6 +3,10 @@
 #
 # HINT: check settings with
 #   git ls-files | git check-attr --stdin --all
+#   git ls-files --eol
+
+# disable all line ending conversions
+* -text
 
 #
 # tell diff tools that these files are generated automatically
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 510f1a86..6965c9f8 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -16,8 +16,9 @@ env:
   UPX_CMAKE_BUILD_FLAGS: --verbose
   UPX_CMAKE_CONFIG_FLAGS: -Wdev --warn-uninitialized
   UPX_DEBUG_TEST_FLOAT_DIVISION_BY_ZERO: 1
-  # 2024-03-29
-  ZIG_DIST_VERSION: 0.12.0-dev.3484+7aa42f47b
+  UPX_DEBUG_TEST_LIBC_QSORT: 1
+  # 2024-04-01
+  ZIG_DIST_VERSION: 0.12.0-dev.3508+a6ed3e6d2
 
 jobs:
   job-rebuild-and-verify-stubs:
@@ -183,7 +184,7 @@ jobs:
   job-macos-cmake: # uses cmake + make
     if: true
     needs: [ job-rebuild-and-verify-stubs ]
-    name: ${{ format('{0} {1}', matrix.os, matrix.xcode_version) }}
+    name: ${{ format('{0} {1}{2}', matrix.os, matrix.xcode_version && 'xcode-' || '',  matrix.xcode_version) }}
     runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false
@@ -193,8 +194,8 @@ jobs:
           # NOTE: macos-11 does not have "readlink -f"; only on macos >= 12 or with brew coreutils
           - { os: macos-11, gcc: gcc-10, gxx: 'g++-10', testsuite: true }
           - { os: macos-12, gcc: gcc-11, gxx: 'g++-11', testsuite: true }
-          - { os: macos-13, gcc: gcc-12, gxx: 'g++-12', testsuite: true, xcode_version: 14.3.1 }
           - { os: macos-13, testsuite: true } # use default Xcode-15
+          - { os: macos-13, gcc: gcc-12, gxx: 'g++-12', testsuite: true, xcode_version: 14.3.1 }
           # { os: macos-14, gcc: gcc-13, gxx: 'g++-13', testsuite: true }                        # gcc-13: INTERNAL ERROR in ld64
           # { os: macos-14, gcc: gcc-13, gxx: 'g++-13', testsuite: true, xcode_version: 14.3.1 } # gcc-13: MISSING HEADER FILES
           - { os: macos-14, gcc: gcc-12, gxx: 'g++-12', testsuite: true } # => use gcc-12 for now
@@ -465,16 +466,18 @@ jobs:
           - { zig_target: aarch64-windows-gnu }
           - { zig_target: arm-linux-musleabihf, qemu: qemu-arm }
           # { zig_target: arm-linux-musleabihf, qemu: qemu-arm, zig_pic: -fPIE }
-          - { zig_target: i386-linux-musl, qemu: qemu-i386 }
-          # { zig_target: i386-linux-musl, qemu: qemu-i386, zig_pic: -fPIE }
+          - { zig_target: i386-linux-gnu.2.3.4, zig_flags: -march=i586 }
+          - { zig_target: i386-linux-musl, zig_flags: -march=i586, qemu: qemu-i386 }
+          # { zig_target: i386-linux-musl, zig_flags: -march=i586, qemu: qemu-i386, zig_pic: -fPIE }
           - { zig_target: i386-windows-gnu }
           # mips and mipsel: bad hard-float code generation(??); or QEMU bug; or UPX bug; see https://github.com/upx/upx/issues/788
           - { zig_target: mips-linux-musl, zig_flags: -msoft-float, qemu: qemu-mips }
           - { zig_target: mipsel-linux-musl, zig_flags: -msoft-float, qemu: qemu-mipsel }
           - { zig_target: powerpc-linux-musl, qemu: qemu-ppc }
-          # powerpc64: obscure problem with C++ exceptions in doctest checks when *NOT* using -fstack-protector
+          # powerpc64: obscure problem with C++ exceptions in UPX doctest checks when *NOT* using -fstack-protector
           - { zig_target: powerpc64-linux-musl, zig_flags: -fstack-protector, qemu: qemu-ppc64 }
           - { zig_target: powerpc64le-linux-musl, qemu: qemu-ppc64le }
+          - { zig_target: x86_64-linux-gnu.2.3.4 }
           - { zig_target: x86_64-linux-musl, qemu: qemu-x86_64 }
           # { zig_target: x86_64-linux-musl, qemu: qemu-x86_64, zig_pic: -fPIE }
           # { zig_target: x86_64-macos-none }
diff --git a/CMakeLists.txt b/CMakeLists.txt
index b1cee4b7..8e890830 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -516,7 +516,7 @@ if(Threads_FOUND)
 elseif(UPX_CONFIG_REQUIRE_THREADS)
     message(FATAL_ERROR "ERROR: WITH_THREADS required")
 elseif(UPX_CONFIG_EXPECT_THREADS AND NOT UPX_CONFIG_DISABLE_THREADS)
-    message(FATAL_ERROR "ERROR: WITH_THREADS expected")
+    message(FATAL_ERROR "ERROR: WITH_THREADS expected; set UPX_CONFIG_EXPECT_THREADS=OFF to disable")
 endif()
 if(CMAKE_BUILD_TYPE AND NOT CMAKE_BUILD_TYPE MATCHES "^(Debug|None|Release)$")
     message(WARNING "WARNING: unsupported CMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}; please use \"Debug\" or \"Release\"")
diff --git a/misc/make/Makefile-extra.mk b/misc/make/Makefile-extra.mk
index ce7b956a..9fc917c5 100644
--- a/misc/make/Makefile-extra.mk
+++ b/misc/make/Makefile-extra.mk
@@ -236,8 +236,8 @@ build/analyze/clang-tidy/debug build/analyze/clang-tidy/release: build/analyze/c
 build/analyze/clang-tidy/debug build/analyze/clang-tidy/release: build/analyze/clang-tidy-zstd/$$(notdir $$@)
 
 # OLD names [deprecated]
-build/extra/scan-build/debug:   build/analyze/clang-analyzer/debug
-build/extra/scan-build/release: build/analyze/clang-analyzer/release
+build/extra/scan-build/debug:   build/analyze/clang-analyzer/debug PHONY
+build/extra/scan-build/release: build/analyze/clang-analyzer/release PHONY
 
 #***********************************************************************
 # advanced: generic eXtra target
diff --git a/src/Makefile b/src/Makefile
index c7ebc97a..630ebcc7 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -33,10 +33,6 @@ debug+test release+test all+test:                   PHONY; $(MAKE) -C $(top_srcd
 
 test:: build/all+test PHONY
 
-# OLD target names [deprecated]
-$(top_srcdir)/build/debug:   build/debug PHONY
-$(top_srcdir)/build/release: build/release PHONY
-
 #***********************************************************************
 # make run-testsuite
 # git clone https://github.com/upx/upx-testsuite.git
diff --git a/src/bele.h b/src/bele.h
index 0e97a241..23f3299b 100644
--- a/src/bele.h
+++ b/src/bele.h
@@ -785,6 +785,26 @@ inline unsigned UPX_MIN(const LE32 &a, unsigned b) { return UPX_MIN(unsigned(a),
 // misc support
 **************************************************************************/
 
+// for use with qsort()
+extern "C" {
+int __acc_cdecl_qsort be16_compare(const void *, const void *);
+int __acc_cdecl_qsort be24_compare(const void *, const void *);
+int __acc_cdecl_qsort be32_compare(const void *, const void *);
+int __acc_cdecl_qsort be64_compare(const void *, const void *);
+int __acc_cdecl_qsort le16_compare(const void *, const void *);
+int __acc_cdecl_qsort le24_compare(const void *, const void *);
+int __acc_cdecl_qsort le32_compare(const void *, const void *);
+int __acc_cdecl_qsort le64_compare(const void *, const void *);
+int __acc_cdecl_qsort be16_compare_signed(const void *, const void *);
+int __acc_cdecl_qsort be24_compare_signed(const void *, const void *);
+int __acc_cdecl_qsort be32_compare_signed(const void *, const void *);
+int __acc_cdecl_qsort be64_compare_signed(const void *, const void *);
+int __acc_cdecl_qsort le16_compare_signed(const void *, const void *);
+int __acc_cdecl_qsort le24_compare_signed(const void *, const void *);
+int __acc_cdecl_qsort le32_compare_signed(const void *, const void *);
+int __acc_cdecl_qsort le64_compare_signed(const void *, const void *);
+} // extern "C"
+
 // <type_traits> upx_is_integral; see conf.h
 #define TT_UPX_IS_INTEGRAL(T)                                                                      \
     template <>                                                                                    \
@@ -826,26 +846,6 @@ typedef LE64 NE64;
 #define ne64_compare_signed le64_compare_signed
 #endif
 
-// for use with qsort()
-extern "C" {
-int __acc_cdecl_qsort be16_compare(const void *, const void *);
-int __acc_cdecl_qsort be24_compare(const void *, const void *);
-int __acc_cdecl_qsort be32_compare(const void *, const void *);
-int __acc_cdecl_qsort be64_compare(const void *, const void *);
-int __acc_cdecl_qsort le16_compare(const void *, const void *);
-int __acc_cdecl_qsort le24_compare(const void *, const void *);
-int __acc_cdecl_qsort le32_compare(const void *, const void *);
-int __acc_cdecl_qsort le64_compare(const void *, const void *);
-int __acc_cdecl_qsort be16_compare_signed(const void *, const void *);
-int __acc_cdecl_qsort be24_compare_signed(const void *, const void *);
-int __acc_cdecl_qsort be32_compare_signed(const void *, const void *);
-int __acc_cdecl_qsort be64_compare_signed(const void *, const void *);
-int __acc_cdecl_qsort le16_compare_signed(const void *, const void *);
-int __acc_cdecl_qsort le24_compare_signed(const void *, const void *);
-int __acc_cdecl_qsort le32_compare_signed(const void *, const void *);
-int __acc_cdecl_qsort le64_compare_signed(const void *, const void *);
-} // extern "C"
-
 /*************************************************************************
 // Provide namespaces and classes to abstract endianness policies.
 //
diff --git a/src/bele_policy.h b/src/bele_policy.h
index b3b36e19..f03f8d07 100644
--- a/src/bele_policy.h
+++ b/src/bele_policy.h
@@ -92,9 +92,9 @@ private:
 #define C const noexcept override
 #endif
 
-struct BEPolicy
+struct BEPolicy final
 #if defined(BELE_RTP)
-    final : public AbstractPolicy
+    : public AbstractPolicy
 #endif
 {
     explicit inline BEPolicy() noexcept {}
@@ -151,9 +151,9 @@ private:
     UPX_CXX_DISABLE_NEW_DELETE(BEPolicy)
 };
 
-struct LEPolicy
+struct LEPolicy final
 #if defined(BELE_RTP)
-    final : public AbstractPolicy
+    : public AbstractPolicy
 #endif
 {
     explicit inline LEPolicy() noexcept {}
diff --git a/src/check/dt_check.cpp b/src/check/dt_check.cpp
index 6c47409a..bc001a66 100644
--- a/src/check/dt_check.cpp
+++ b/src/check/dt_check.cpp
@@ -24,6 +24,9 @@
    <markus@oberhumer.com>
  */
 
+// doctest checks, and various tests to catch toolchain/qemu/sanitizer/valgrind/wine/etc
+// problems; grown historically
+
 #include "../util/system_headers.h"
 #include <cmath> // std::isinf std::isnan
 #include "../conf.h"
@@ -376,6 +379,7 @@ struct TestFloat {
     static noinline Float add_div_x(Int a, Int b) { return Float(a + b) / Float(X); }
     static noinline Float sub_div_x(Int a, Int b) { return Float(a - b) / Float(X); }
     static noinline void check() noexcept {
+        assert_noexcept(div(2 * X, Float(X)) == Float(2));
         assert_noexcept(add_div(X, X, Float(X)) == Float(2));
         assert_noexcept(add_div_x(X, X) == Float(2));
         assert_noexcept(sub_div(3 * X, X, Float(X)) == Float(2));
@@ -391,6 +395,7 @@ struct TestFloat {
 #else
             assert_noexcept(std::isnan(div(0, Float(0))));
             assert_noexcept(std::isinf(div(1, Float(0))));
+            assert_noexcept(std::isinf(div(Int(-1), Float(0))));
 #endif
         }
     }
@@ -432,6 +437,19 @@ void upx_compiler_sanity_check(void) noexcept {
 
     check_basic_floating_point();
 
+    // check_basic_decltype()
+    {
+        auto a = +0;
+        constexpr auto b = -0;
+        const auto &c = -1;
+        COMPILE_TIME_ASSERT((std::is_same<int, decltype(a)>::value))
+        COMPILE_TIME_ASSERT((std::is_same<const int, decltype(b)>::value))
+        COMPILE_TIME_ASSERT((std::is_same<const int &, decltype(c)>::value))
+        UNUSED(a);
+        UNUSED(b);
+        UNUSED(c);
+    }
+
 #define ACC_WANT_ACC_CHK_CH 1
 #undef ACCCHK_ASSERT
 #define ACCCHK_ASSERT(expr) ACC_COMPILE_TIME_ASSERT(expr)
@@ -646,7 +664,7 @@ void upx_compiler_sanity_check(void) noexcept {
 **************************************************************************/
 
 TEST_CASE("assert_noexcept") {
-    // just to make sure that our own assert() macros don't generate any warnings
+    // just to make sure that our own assert() macros do not trigger any compiler warnings
     byte dummy = 0;
     byte *ptr1 = &dummy;
     const byte *const ptr2 = &dummy;
@@ -668,10 +686,13 @@ TEST_CASE("acc_vget") {
     CHECK_EQ(acc_vget_long(1, -1), 1);
     CHECK_EQ(acc_vget_acc_int64l_t(2, 1), 2);
     CHECK_EQ(acc_vget_acc_hvoid_p(nullptr, 0), nullptr);
+    if (acc_vget_int(1, 0) > 0)
+        return;
+    assert_noexcept(false);
 }
 
 TEST_CASE("ptr_invalidate_and_poison") {
-    int *ip = nullptr;
+    int *ip = nullptr; // initialized
     ptr_invalidate_and_poison(ip);
     assert(ip != nullptr);
     (void) ip;
@@ -751,11 +772,13 @@ TEST_CASE("libc snprintf") {
     CHECK_EQ(strcmp(buf, "0X1A   0x1b   0x1c  "), 0);
 }
 
-#if 0
 TEST_CASE("libc qsort") {
     // runtime check that libc qsort() never compares identical objects
-    // UPDATE: while only poor implementations of qsort() would actually do
-    //   this, it is probably allowed by the standard; so skip this test case
+    // UPDATE: while only poor implementations of qsort() would actually do this
+    //   it is probably allowed by the standard, so skip this test by default
+    if (!is_envvar_true("UPX_DEBUG_TEST_LIBC_QSORT"))
+        return;
+
     struct Elem {
         upx_uint16_t id;
         upx_uint16_t value;
@@ -765,8 +788,8 @@ TEST_CASE("libc qsort") {
             assert_noexcept(a->id != b->id); // check not IDENTICAL
             return a->value < b->value ? -1 : (a->value == b->value ? 0 : 1);
         }
-        static bool check_sort(upx_sort_func_t sort, Elem *e, size_t n) {
-            upx_uint32_t x = 5381 + n + ((upx_uintptr_t) e & 0xff);
+        static noinline bool check_sort(upx_sort_func_t sort, Elem *e, size_t n) {
+            upx_uint32_t x = 5381 + n + (upx_rand() & 0xff);
             for (size_t i = 0; i < n; i++) {
                 e[i].id = (upx_uint16_t) i;
                 x = x * 33 + 1 + (i & 255);
@@ -782,18 +805,19 @@ TEST_CASE("libc qsort") {
     constexpr size_t N = 4096;
     Elem e[N];
     for (size_t n = 0; n <= N; n = 2 * n + 1) {
-        // CHECK(Elem::check_sort(qsort, e, n)); // libc qsort()
-        CHECK(Elem::check_sort(upx_gnomesort, e, n));
-        CHECK(Elem::check_sort(upx_shellsort_memswap, e, n));
-        CHECK(Elem::check_sort(upx_shellsort_memcpy, e, n));
+        // system sort functions
+        CHECK(Elem::check_sort(::qsort, e, n)); // libc qsort()
 #if UPX_CONFIG_USE_STABLE_SORT
         upx_sort_func_t wrap_stable_sort = [](void *aa, size_t nn, size_t, upx_compare_func_t cc) {
             upx_std_stable_sort<sizeof(Elem)>(aa, nn, cc);
         };
-        CHECK(Elem::check_sort(wrap_stable_sort, e, n));
+        CHECK(Elem::check_sort(wrap_stable_sort, e, n)); // std::stable_sort()
 #endif
+        // UPX sort functions
+        CHECK(Elem::check_sort(upx_gnomesort, e, n));
+        CHECK(Elem::check_sort(upx_shellsort_memswap, e, n));
+        CHECK(Elem::check_sort(upx_shellsort_memcpy, e, n));
     }
 }
-#endif
 
 /* vim:set ts=4 sw=4 et: */
diff --git a/src/check/dt_cxxlib.cpp b/src/check/dt_cxxlib.cpp
index c4ba68b8..15b3426b 100644
--- a/src/check/dt_cxxlib.cpp
+++ b/src/check/dt_cxxlib.cpp
@@ -27,24 +27,8 @@
 // lots of tests (and probably quite a number of redundant tests)
 // modern compilers will optimize away much of this code
 
-#if 0 // TODO later
-// libc++ hardenining
-#if defined(__clang__) && defined(__clang_major__) && (__clang_major__ + 0 >= 18)
-#if DEBUG
-#define _LIBCPP_HARDENING_MODE _LIBCPP_HARDENING_MODE_DEBUG
-#else
-#define _LIBCPP_HARDENING_MODE _LIBCPP_HARDENING_MODE_EXTENSIVE
-#endif
-#endif
-#if defined(__clang__) && defined(__clang_major__) && (__clang_major__ + 0 < 18)
-#if DEBUG
-#define _LIBCPP_ENABLE_ASSERTIONS 1
-#endif
-#endif
-#endif // TODO later
-
 #include "../util/system_headers.h"
-#include <vector>
+#include <vector> // std::vector
 #include "../conf.h"
 
 /*************************************************************************
@@ -125,7 +109,7 @@ ACC_COMPILE_TIME_ASSERT_HEADER(compile_time::string_le("abc", "abz"))
 //
 **************************************************************************/
 
-TEST_CASE("libc++") {
+TEST_CASE("std::vector") {
     constexpr size_t N = 16;
     std::vector<int> v(N);
     CHECK(v.end() - v.begin() == N);
@@ -298,7 +282,7 @@ TEST_CASE("upx::ObjectDeleter 2") {
 }
 
 TEST_CASE("upx::ptr_static_cast") {
-    // check that we don't trigger any -Wcast-align warnings
+    // check that we do not trigger any -Wcast-align warnings
     using upx::ptr_static_cast;
     void *vp = nullptr;
     byte *bp = nullptr;
diff --git a/src/conf.h b/src/conf.h
index 70f3422a..44521979 100644
--- a/src/conf.h
+++ b/src/conf.h
@@ -162,7 +162,7 @@ ACC_COMPILE_TIME_ASSERT_HEADER(sizeof(upx_charptr_unit_type) == 1)
 typedef upx_int64_t upx_off_t;
 #undef off_t
 #if 0
-// TODO cleanup: at some future point we can do this:
+// TODO later cleanup: at some future point we can do this:
 #define off_t DO_NOT_USE_off_t
 #else
 #define off_t upx_off_t
@@ -230,12 +230,6 @@ typedef upx_int64_t upx_off_t;
 #undef sopen
 #endif
 
-#if defined(HAVE_DUP) && (HAVE_DUP + 0 == 0)
-// TODO later: add upx_fd_dup() util
-#undef dup
-#define dup(x) (-1)
-#endif
-
 #ifndef STDIN_FILENO
 #define STDIN_FILENO (fileno(stdin))
 #endif
@@ -338,7 +332,7 @@ typedef upx_int64_t upx_off_t;
 // TODO later: check __MINGW_PRINTF_FORMAT
 #if defined(_WIN32) && defined(__MINGW32__) && defined(__GNUC__) && !defined(__clang__)
 #define attribute_format(a, b) __attribute__((__format__(__gnu_printf__, a, b)))
-#elif (ACC_CC_CLANG || ACC_CC_GNUC)
+#elif defined(__clang__) || defined(__GNUC__)
 #define attribute_format(a, b) __attribute__((__format__(__printf__, a, b)))
 #else
 #define attribute_format(a, b) /*empty*/
@@ -442,6 +436,7 @@ inline void mem_clear(T *object) noexcept {
     static_assert(size >= 1 && size <= UPX_RSIZE_MAX_MEM);
     memset((void *) object, 0, size);
 }
+// disable some overloads
 #if defined(__clang__) || __GNUC__ != 7
 template <class T>
 inline void mem_clear(T (&array)[]) noexcept DELETED_FUNCTION;
diff --git a/src/except.cpp b/src/except.cpp
index 00bb8951..acf8d0c9 100644
--- a/src/except.cpp
+++ b/src/except.cpp
@@ -203,7 +203,7 @@ const char *prettyName(const char *n) noexcept {
             n++;
         else if (*n == ' ')
             n++;
-        else if (strncmp(n, "class ", 6) == 0) // Visual C++ (msvc)
+        else if (strncmp(n, "class ", 6) == 0) // Visual C++ (MSVC)
             n += 6;
         else
             break;
diff --git a/src/file.cpp b/src/file.cpp
index 735378e8..2cfc9026 100644
--- a/src/file.cpp
+++ b/src/file.cpp
@@ -40,6 +40,7 @@
 #else
     UNUSED(name);
     UNUSED(mode);
+    // no error
 #endif
 }
 
@@ -88,7 +89,7 @@ bool FileBase::do_sopen() {
     else {
 #if (ACC_OS_DOS32) && defined(__DJGPP__)
         _fd = ::open(_name, _flags | _shflags, _mode);
-#elif defined(__MINT__)
+#elif (ACC_ARCH_M68K && ACC_OS_TOS && ACC_CC_GNUC) && defined(__MINT__)
         _fd = ::open(_name, _flags | (_shflags & O_SHMODE), _mode);
 #elif defined(SH_DENYRW)
         _fd = ::sopen(_name, _flags, _shflags, _mode);
@@ -98,6 +99,7 @@ bool FileBase::do_sopen() {
     }
     if (_fd < 0)
         return false;
+    st.st_size = 0;
     if (::fstat(_fd, &st) != 0)
         throwIOException(_name, errno);
     _length = st.st_size;
@@ -212,6 +214,20 @@ upx_off_t InputFile::seek(upx_off_t off, int whence) {
 
 upx_off_t InputFile::st_size_orig() const { return _length_orig; }
 
+int InputFile::dup() may_throw {
+    if (!isOpen())
+        throwIOException("bad dup");
+#if defined(HAVE_DUP) && (HAVE_DUP + 0 == 0)
+    errno = ENOSYS;
+    int r = -1;
+#else
+    int r = ::dup(getFd());
+#endif
+    if (r < 0)
+        throwIOException("dup", errno);
+    return r;
+}
+
 /*************************************************************************
 // OutputFile
 **************************************************************************/
@@ -333,6 +349,7 @@ void OutputFile::set_extent(upx_off_t offset, upx_off_t length) {
     super::set_extent(offset, length);
     bytes_written = 0;
     if (0 == offset && 0xffffffffLL == length) { // TODO: check all callers of this method
+        st.st_size = 0;
         if (::fstat(_fd, &st) != 0)
             throwIOException(_name, errno);
         _length = st.st_size - offset;
diff --git a/src/file.h b/src/file.h
index 435b5ba3..cca45e92 100644
--- a/src/file.h
+++ b/src/file.h
@@ -88,6 +88,8 @@ public:
     virtual upx_off_t seek(upx_off_t off, int whence) override;
     upx_off_t st_size_orig() const;
 
+    noinline int dup() may_throw;
+
 protected:
     upx_off_t _length_orig = 0;
 };
diff --git a/src/linker.cpp b/src/linker.cpp
index 7775569e..4a8efaa4 100644
--- a/src/linker.cpp
+++ b/src/linker.cpp
@@ -60,7 +60,7 @@ ElfLinker::Section::Section(const char *n, const void *i, unsigned s, unsigned a
     : name(nullptr), output(nullptr), size(s), offset(0), p2align(a), next(nullptr) {
     name = strdup(n);
     assert(name != nullptr);
-    input = malloc(s + 1);
+    input = ::malloc(s + 1);
     assert(input != nullptr);
     if (s != 0) {
         assert(i != nullptr);
@@ -70,8 +70,8 @@ ElfLinker::Section::Section(const char *n, const void *i, unsigned s, unsigned a
 }
 
 ElfLinker::Section::~Section() noexcept {
-    free(name);
-    free(input);
+    ::free(name);
+    ::free(input);
 }
 
 /*************************************************************************
@@ -85,7 +85,7 @@ ElfLinker::Symbol::Symbol(const char *n, Section *s, upx_uint64_t o)
     assert(section != nullptr);
 }
 
-ElfLinker::Symbol::~Symbol() noexcept { free(name); }
+ElfLinker::Symbol::~Symbol() noexcept { ::free(name); }
 
 /*************************************************************************
 // Relocation
@@ -110,13 +110,13 @@ ElfLinker::~ElfLinker() noexcept {
     unsigned ic;
     for (ic = 0; ic < nsections; ic++)
         delete sections[ic];
-    free(sections);
+    ::free(sections);
     for (ic = 0; ic < nsymbols; ic++)
         delete symbols[ic];
-    free(symbols);
+    ::free(symbols);
     for (ic = 0; ic < nrelocations; ic++)
         delete relocations[ic];
-    free(relocations);
+    ::free(relocations);
 }
 
 void ElfLinker::init(const void *pdata_v, int plen, unsigned pxtra) {
@@ -425,7 +425,7 @@ int ElfLinker::addLoader(const char *sname) {
         }
         sect += strlen(sect) + 1;
     }
-    free(begin);
+    ::free(begin);
     return outputlen;
 }
 
diff --git a/src/main.cpp b/src/main.cpp
index 9f99ba12..069fc9bb 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -923,7 +923,7 @@ int main_get_options(int argc, char **argv) {
         // atari/tos
         {"split-segments", 0x90, N, 650},
         // darwin/macho
-        {"force-macos", 0x90, N, 690}, // undocumented temporary until we fix macOS 13+
+        {"force-macos", 0x90, N, 690}, // undocumented temporary option until we do fix macOS 13+
         // djgpp2/coff
         {"coff", 0x90, N, 610}, // produce COFF output
         // dos/exe
@@ -1355,9 +1355,9 @@ int __acc_cdecl_main main(int argc, char *argv[]) /*noexcept*/ {
 #endif
     acc_wildargv(&argc, &argv);
 #if defined(__wasi__)
-    srand((int) time(nullptr));
+    ::srand((unsigned) time(nullptr));
 #else
-    srand((int) clock());
+    ::srand((unsigned) clock());
 #endif
 
     // info: main() is implicitly "noexcept", so we need a try block
diff --git a/src/options.h b/src/options.h
index a01d6398..65709620 100644
--- a/src/options.h
+++ b/src/options.h
@@ -28,9 +28,10 @@
 #pragma once
 
 struct Options;
-extern Options *opt;      // global options, see class PackMaster for per-file local options
 #define options_t Options // old name
 
+extern Options *opt; // global options, see class PackMaster for per-file local options
+
 #if WITH_THREADS
 extern std::mutex opt_lock_mutex;
 #endif
@@ -177,6 +178,9 @@ struct Options final {
         int strip_relocs;
         const char *keep_resource;
     } win32_pe;
+
+private: // UPX conventions
+    UPX_CXX_DISABLE_NEW_DELETE(Options)
 };
 
 /* vim:set ts=4 sw=4 et: */
diff --git a/src/p_vmlinz.cpp b/src/p_vmlinz.cpp
index 7123967d..62aec6e8 100644
--- a/src/p_vmlinz.cpp
+++ b/src/p_vmlinz.cpp
@@ -267,7 +267,7 @@ int PackVmlinuzI386::decompressKernel()
             fd_pos = -1;
             // open
             fi->seek(gzoff, SEEK_SET);
-            fd = dup(fi->getFd());
+            fd = fi->dup();
             if (fd < 0)
                 break;
             gzFile zf = gzdopen(fd, "rb");
@@ -849,7 +849,7 @@ int PackVmlinuzARMEL::decompressKernel()
             fd_pos = -1;
             // open
             fi->seek(gzoff, SEEK_SET);
-            fd = dup(fi->getFd());
+            fd = fi->dup();
             if (fd < 0)
                 break;
             gzFile zf = gzdopen(fd, "rb");
diff --git a/src/p_wcle.cpp b/src/p_wcle.cpp
index ab7c9bbc..54cb0c23 100644
--- a/src/p_wcle.cpp
+++ b/src/p_wcle.cpp
@@ -743,6 +743,7 @@ tribool PackWcle::canUnpack() {
     return readPackHeader(len) ? 1 : -1;
 }
 
+/*static*/
 void PackWcle::virt2rela(const le_object_table_entry_t *entr, unsigned *objn, unsigned *addr) {
     for (; *objn > 1; objn[0]--) {
         if (entr[*objn - 1].my_base_address > *addr)
diff --git a/src/packer.cpp b/src/packer.cpp
index 30f729e7..795503ef 100644
--- a/src/packer.cpp
+++ b/src/packer.cpp
@@ -495,7 +495,7 @@ unsigned Packer::getRandomId() const {
 #endif
         id ^= (unsigned) fi->st.st_ino;
         id ^= (unsigned) fi->st.st_atime;
-        id ^= (unsigned) rand();
+        id ^= (unsigned) upx_rand();
     }
     return id;
 }
@@ -947,7 +947,7 @@ int Packer::prepareMethods(int *methods, int ph_method, const int *all_methods)
     }
     // debug
     if (opt->debug.use_random_method && nmethods >= 2) {
-        int method = methods[rand() % nmethods];
+        int method = methods[upx_rand() % nmethods];
         methods[0] = method;
         nmethods = 1;
         NO_printf("\nuse_random_method = %d\n", method);
@@ -1015,7 +1015,7 @@ done:
         filters[nfilters++] = 0;
     // debug
     if (opt->debug.use_random_filter && nfilters >= 3 && filters[nfilters - 1] == 0) {
-        int filter_id = filters[rand() % (nfilters - 1)];
+        int filter_id = filters[upx_rand() % (nfilters - 1)];
         if (filter_id > 0) {
             filters[0] = filter_id;
             filters[1] = 0;
diff --git a/src/packhead.h b/src/packhead.h
index bf97f612..dd8d137b 100644
--- a/src/packhead.h
+++ b/src/packhead.h
@@ -84,10 +84,14 @@ struct PackHeader final {
 
     // info fields set by Packer::compressWithFilters()
     unsigned overlap_overhead;
+
+private: // UPX conventions
+    UPX_CXX_DISABLE_ADDRESS(PackHeader)
+    UPX_CXX_DISABLE_NEW_DELETE(PackHeader)
 };
 
 /*************************************************************************
-// ph default util functions
+// PackHeader ph util functions
 **************************************************************************/
 
 bool ph_is_forced_method(int method) noexcept; // predicate
diff --git a/src/packmast.h b/src/packmast.h
index d47ad01d..98337e12 100644
--- a/src/packmast.h
+++ b/src/packmast.h
@@ -59,6 +59,11 @@ private:
     // setup local options for each file
     Options local_options;
     Options *saved_opt = nullptr;
+
+private: // UPX conventions
+    UPX_CXX_DISABLE_ADDRESS(PackMaster)
+    UPX_CXX_DISABLE_COPY_MOVE(PackMaster)
+    UPX_CXX_DISABLE_NEW_DELETE(PackMaster)
 };
 
 /* vim:set ts=4 sw=4 et: */
diff --git a/src/pefile.cpp b/src/pefile.cpp
index 0144a88f..b161ed20 100644
--- a/src/pefile.cpp
+++ b/src/pefile.cpp
@@ -215,7 +215,7 @@ int PeFile::readFileHeader() {
 
 PeFile::Interval::Interval(SPAN_P(byte) b) : base(b) {}
 
-PeFile::Interval::~Interval() noexcept { free(ivarr); }
+PeFile::Interval::~Interval() noexcept { ::free(ivarr); }
 
 int __acc_cdecl_qsort PeFile::Interval::compare(const void *p1, const void *p2) {
     const interval *i1 = (const interval *) p1;
@@ -1175,14 +1175,14 @@ PeFile::Export::Export(char *_base) : base(_base), iv((byte *) _base) {
 }
 
 PeFile::Export::~Export() noexcept {
-    free(ename);
+    ::free(ename);
     delete[] functionptrs;
     delete[] ordinals;
     if (names) {
         const unsigned limit = edir.names + edir.functions;
         for (unsigned ic = 0; ic < limit; ic++)
             if (names[ic])
-                free(names[ic]); // allocated by strdup()
+                ::free(names[ic]); // allocated by strdup()
         delete[] names;
     }
 }
diff --git a/src/ui.h b/src/ui.h
index 51407636..e41b2289 100644
--- a/src/ui.h
+++ b/src/ui.h
@@ -104,6 +104,10 @@ protected:
     static unsigned update_u_len;
     static unsigned update_fc_len;
     static unsigned update_fu_len;
+
+private: // UPX conventions
+    UPX_CXX_DISABLE_ADDRESS(UiPacker)
+    UPX_CXX_DISABLE_COPY_MOVE(UiPacker)
 };
 
 /* vim:set ts=4 sw=4 et: */
diff --git a/src/util/cxxlib.h b/src/util/cxxlib.h
index 6cd85f01..2b88b5cf 100644
--- a/src/util/cxxlib.h
+++ b/src/util/cxxlib.h
@@ -427,7 +427,7 @@ template <class T>
 inline void owner_free(OwningPointer(T)(&object)) noexcept {
     static_assert(!std::is_class_v<T>); // UPX convention
     if (object != nullptr) {
-        free((T *) object);
+        ::free((T *) object);
         object = nullptr;
     }
     assert_noexcept((T *) object == nullptr);
diff --git a/src/util/snprintf.cpp b/src/util/snprintf.cpp
index 22085bf2..81d4d938 100644
--- a/src/util/snprintf.cpp
+++ b/src/util/snprintf.cpp
@@ -128,7 +128,7 @@ int upx_safe_vasprintf(char **ptr, const char *format, va_list ap) {
     va_end(ap_copy);
 
     if (len >= 0) {
-        *ptr = (char *) malloc(len + 1);
+        *ptr = (char *) ::malloc(len + 1);
         assert(*ptr != nullptr);
         if (*ptr == nullptr)
             return -1;
diff --git a/src/util/system_features.h b/src/util/system_features.h
index 1b2bc864..b8233a1f 100644
--- a/src/util/system_features.h
+++ b/src/util/system_features.h
@@ -55,7 +55,7 @@
 #if DEBUG
 #define _LIBCPP_ENABLE_ASSERTIONS 1
 #endif
-#endif
+#endif // clang >= 18
 #endif // TODO later
 
 /* vim:set ts=4 sw=4 et: */
diff --git a/src/util/util.cpp b/src/util/util.cpp
index 34d6eb6e..7644e771 100644
--- a/src/util/util.cpp
+++ b/src/util/util.cpp
@@ -254,17 +254,19 @@ TEST_CASE("ptr_check_no_overlap 3") {
 // stdlib
 **************************************************************************/
 
+int upx_rand(void) noexcept { return ::rand(); }
+
 void *upx_calloc(size_t n, size_t element_size) may_throw {
     size_t bytes = mem_size(element_size, n); // assert size
-    void *p = malloc(bytes);
+    void *p = ::malloc(bytes);
     if (p != nullptr)
         memset(p, 0, bytes);
     return p;
 }
 
 // simple unoptimized memswap()
-void upx_memswap(void *a, void *b, size_t n) noexcept {
-    if (a != b && n != 0) {
+void upx_memswap(void *a, void *b, size_t bytes) noexcept {
+    if (a != b && bytes != 0) {
         byte *x = (byte *) a;
         byte *y = (byte *) b;
         do {
@@ -273,16 +275,16 @@ void upx_memswap(void *a, void *b, size_t n) noexcept {
             byte tmp = *x; // NOLINT(*core.uninitialized.Assign) // bogus clang-analyzer warning
             *x++ = *y;
             *y++ = tmp;
-        } while (--n != 0);
+        } while (--bytes != 0);
     }
 }
 
 // much better memswap(), optimized for our use case in sort functions below
-static void memswap_no_overlap(byte *a, byte *b, size_t n) noexcept {
+static inline void memswap_no_overlap(byte *a, byte *b, size_t bytes) noexcept {
 #if defined(__clang__) && __clang_major__ < 15
     // work around a clang < 15 ICE (Internal Compiler Error)
     // @COMPILER_BUG @CLANG_BUG
-    upx_memswap(a, b, n);
+    upx_memswap(a, b, bytes);
 #else // clang bug
     upx_alignas_max byte tmp_buf[16];
 #define SWAP(x)                                                                                    \
@@ -294,15 +296,15 @@ static void memswap_no_overlap(byte *a, byte *b, size_t n) noexcept {
         b += x;                                                                                    \
     } while (0)
 
-    for (; n >= 16; n -= 16)
+    for (; bytes >= 16; bytes -= 16)
         SWAP(16);
-    if (n & 8)
+    if (bytes & 8)
         SWAP(8);
-    if (n & 4)
+    if (bytes & 4)
         SWAP(4);
-    if (n & 2)
+    if (bytes & 2)
         SWAP(2);
-    if (n & 1) {
+    if (bytes & 1) {
         byte tmp = *a;
         *a = *b;
         *b = tmp;
@@ -347,7 +349,7 @@ void upx_shellsort_memcpy(void *array, size_t n, size_t element_size, upx_compar
     upx_alignas_max byte tmp_buf[MAX_INLINE_ELEMENT_SIZE]; // buffer for one element
     byte *tmp = tmp_buf;
     if (element_size > MAX_INLINE_ELEMENT_SIZE) {
-        tmp = (byte *) malloc(element_size);
+        tmp = (byte *) ::malloc(element_size);
         assert(tmp != nullptr);
     }
     size_t gap = 0;         // 0, 1, 4, 13, 40, 121, 364, 1093, ...
@@ -368,7 +370,7 @@ void upx_shellsort_memcpy(void *array, size_t n, size_t element_size, upx_compar
             }
     }
     if (element_size > MAX_INLINE_ELEMENT_SIZE)
-        free(tmp);
+        ::free(tmp);
 }
 
 // wrap std::stable_sort()
@@ -391,9 +393,10 @@ void upx_std_stable_sort(void *array, size_t n, upx_compare_func_t compare) {
 }
 
 #if UPX_CONFIG_USE_STABLE_SORT
-// instantiate function templates for all element sizes we need; efficient run time, but code size
-// bloat (about 4KiB code size for each function with my current libstdc++); not really needed as
-// libc qsort() is good enough for our use cases
+// instantiate function templates for all element sizes we need; efficient
+// run-time, but code size bloat (about 4KiB code size for each function
+// with my current libstdc++); not really needed as libc qsort() is
+// good enough for our use cases
 template void upx_std_stable_sort<1>(void *, size_t, upx_compare_func_t);
 template void upx_std_stable_sort<2>(void *, size_t, upx_compare_func_t);
 template void upx_std_stable_sort<4>(void *, size_t, upx_compare_func_t);
@@ -405,7 +408,7 @@ template void upx_std_stable_sort<56>(void *, size_t, upx_compare_func_t);
 template void upx_std_stable_sort<72>(void *, size_t, upx_compare_func_t);
 #endif
 
-#if !defined(DOCTEST_CONFIG_DISABLE) && DEBUG >= 1
+#if !defined(DOCTEST_CONFIG_DISABLE) && DEBUG
 #if __cplusplus >= 202002L // use C++20 std::next_permutation() to test all permutations
 namespace {
 template <class ElementType, upx_compare_func_t CompareFunc>
@@ -588,7 +591,7 @@ int find(const void *buf, int blen, const void *what, int wlen) noexcept {
         return -1;
 
     const byte *b = (const byte *) buf;
-    byte first_byte = *(const byte *) what;
+    const byte first_byte = *(const byte *) what;
 
     blen -= wlen;
     for (int i = 0; i <= blen; i++, b++)
@@ -769,8 +772,8 @@ int fn_strcmp(const char *n1, const char *n2) {
 // misc
 **************************************************************************/
 
+// UPX convention: any environment variable that is set and is not strictly equal to "0" is true
 bool is_envvar_true(const char *envvar, const char *alternate_name) noexcept {
-    // UPX convention: any environment variable that is set and is not strictly equal to "0" is true
     const char *e = getenv(envvar);
     if (e != nullptr && e[0])
         return strcmp(e, "0") != 0;
diff --git a/src/util/util.h b/src/util/util.h
index 26d8bc4b..adf183c8 100644
--- a/src/util/util.h
+++ b/src/util/util.h
@@ -143,9 +143,11 @@ inline void ptr_invalidate_and_poison(T *(&ptr)) noexcept {
 // stdlib
 **************************************************************************/
 
-void *upx_calloc(size_t n, size_t element_size) may_throw;
+noinline void *upx_calloc(size_t n, size_t element_size) may_throw;
 
-void upx_memswap(void *a, void *b, size_t n) noexcept;
+void upx_memswap(void *a, void *b, size_t bytes) noexcept;
+
+noinline int upx_rand(void) noexcept;
 
 typedef int(__acc_cdecl_qsort *upx_compare_func_t)(const void *, const void *);
 typedef void (*upx_sort_func_t)(void *array, size_t n, size_t element_size, upx_compare_func_t);
@@ -165,7 +167,7 @@ void upx_std_stable_sort(void *array, size_t n, upx_compare_func_t compare);
     upx_std_stable_sort<(element_size)>((a), (n), (compare))
 #else
 // use libc qsort(); good enough for our use cases
-#define upx_qsort qsort
+#define upx_qsort ::qsort
 #endif
 
 /*************************************************************************
diff --git a/src/work.cpp b/src/work.cpp
index 9bed93b2..3f4bf6c1 100644
--- a/src/work.cpp
+++ b/src/work.cpp
@@ -30,7 +30,7 @@
 // of class PackerBase which then does the actual work.
 // And see p_com.cpp for a simple executable format.
 //
-// This file also has the burden to deal with all those pesky low-level
+// And this file also has the burden to deal with all those pesky low-level
 // file handling issues.
 
 #define WANT_WINDOWS_LEAN_H 1 // _get_osfhandle, GetFileTime, SetFileTime
@@ -47,7 +47,7 @@
 #include "util/membuffer.h"
 
 #if USE_UTIMENSAT && defined(AT_FDCWD)
-#elif (defined(_WIN32) || defined(__CYGWIN__)) && 1
+#elif defined(_WIN32) || defined(__CYGWIN__)
 #define USE_SETFILETIME 1
 #elif (ACC_OS_DOS32) && defined(__DJGPP__)
 #define USE_FTIME 1