diff --git a/windows/vs2015/libyara/libyara.vcxproj b/windows/vs2015/libyara/libyara.vcxproj
index 0980b700..a28058af 100644
--- a/windows/vs2015/libyara/libyara.vcxproj
+++ b/windows/vs2015/libyara/libyara.vcxproj
@@ -78,7 +78,7 @@
   </PropertyGroup>
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
     <ClCompile>
-      <PreprocessorDefinitions>_CRT_SECURE_NO_WARNINGS;CUCKOO_MODULE;HASH_MODULE;DOTNET_MODULE;HAVE_LIBCRYPTO</PreprocessorDefinitions>
+      <PreprocessorDefinitions>_CRT_SECURE_NO_WARNINGS;CUCKOO_MODULE;HASH_MODULE;DOTNET_MODULE;HAVE_LIBCRYPTO;USE_WINDOWS_PROC</PreprocessorDefinitions>
       <AdditionalIncludeDirectories>..\..\..\libyara;..\..\..\libyara\include;..\..\..;..\packages\YARA.Jansson.x86.1.1.0\include;..\packages\YARA.OpenSSL.x86.1.1.0\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <DisableSpecificWarnings>4005;4273;4090</DisableSpecificWarnings>
       <CompileAs>CompileAsCpp</CompileAs>
@@ -105,7 +105,7 @@
   </ItemDefinitionGroup>
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">
     <ClCompile>
-      <PreprocessorDefinitions>_CRT_SECURE_NO_WARNINGS;CUCKOO_MODULE;HASH_MODULE;DOTNET_MODULE;HAVE_LIBCRYPTO</PreprocessorDefinitions>
+      <PreprocessorDefinitions>_CRT_SECURE_NO_WARNINGS;CUCKOO_MODULE;HASH_MODULE;DOTNET_MODULE;HAVE_LIBCRYPTO;USE_WINDOWS_PROC</PreprocessorDefinitions>
       <AdditionalIncludeDirectories>..\..\..\libyara;..\..\..\libyara\include;..\..\..;..\packages\YARA.Jansson.x64.1.1.0\include;..\packages\YARA.OpenSSL.x64.1.1.0\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <DisableSpecificWarnings>4005;4273;4090</DisableSpecificWarnings>
       <CompileAs>CompileAsCpp</CompileAs>
@@ -132,7 +132,7 @@
   </ItemDefinitionGroup>
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
     <ClCompile>
-      <PreprocessorDefinitions>_CRT_SECURE_NO_WARNINGS;CUCKOO_MODULE;HASH_MODULE;DOTNET_MODULE;HAVE_LIBCRYPTO</PreprocessorDefinitions>
+      <PreprocessorDefinitions>_CRT_SECURE_NO_WARNINGS;CUCKOO_MODULE;HASH_MODULE;DOTNET_MODULE;HAVE_LIBCRYPTO;USE_WINDOWS_PROC</PreprocessorDefinitions>
       <AdditionalIncludeDirectories>..\..\..\libyara;..\..\..\libyara\include;..\..\..;..\packages\YARA.Jansson.x86.1.1.0\include;..\packages\YARA.OpenSSL.x86.1.1.0\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <DisableSpecificWarnings>4005;4273;4090</DisableSpecificWarnings>
       <CompileAs>CompileAsCpp</CompileAs>
@@ -157,7 +157,7 @@
   </ItemDefinitionGroup>
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'">
     <ClCompile>
-      <PreprocessorDefinitions>_CRT_SECURE_NO_WARNINGS;CUCKOO_MODULE;HASH_MODULE;DOTNET_MODULE;HAVE_LIBCRYPTO</PreprocessorDefinitions>
+      <PreprocessorDefinitions>_CRT_SECURE_NO_WARNINGS;CUCKOO_MODULE;HASH_MODULE;DOTNET_MODULE;HAVE_LIBCRYPTO;USE_WINDOWS_PROC</PreprocessorDefinitions>
       <AdditionalIncludeDirectories>..\..\..\libyara;..\..\..\libyara\include;..\..\..;..\packages\YARA.Jansson.x64.1.1.0\include;..\packages\YARA.OpenSSL.x64.1.1.0\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <DisableSpecificWarnings>4005;4273;4090</DisableSpecificWarnings>
       <CompileAs>CompileAsCpp</CompileAs>