diff --git a/libs/win32/mpg123/libmpg123.2008.vcproj b/libs/win32/mpg123/libmpg123.2008.vcproj
index 4dc2e3dc08..92f6ede7d7 100644
--- a/libs/win32/mpg123/libmpg123.2008.vcproj
+++ b/libs/win32/mpg123/libmpg123.2008.vcproj
@@ -42,7 +42,7 @@
 				Name="VCCLCompilerTool"
 				Optimization="0"
 				AdditionalIncludeDirectories="src;"$(ProjectDir)libmpg123""
-				PreprocessorDefinitions="WIN32;_DEBUG;_LIB;_CRT_SECURE_NO_DEPRECATE;_CRT_NONSTDC_NO_DEPRECATE"
+				PreprocessorDefinitions="WIN32;_DEBUG;_LIB;_CRT_SECURE_NO_DEPRECATE;_CRT_NONSTDC_NO_DEPRECATE;OPT_GENERIC"
 				MinimalRebuild="true"
 				BasicRuntimeChecks="3"
 				RuntimeLibrary="3"
@@ -112,7 +112,7 @@
 			<Tool
 				Name="VCCLCompilerTool"
 				AdditionalIncludeDirectories="src;&quot;$(ProjectDir)libmpg123&quot;"
-				PreprocessorDefinitions="WIN32;NDEBUG;_LIB;_CRT_SECURE_NO_DEPRECATE;_CRT_NONSTDC_NO_DEPRECATE"
+				PreprocessorDefinitions="WIN32;NDEBUG;_LIB;_CRT_SECURE_NO_DEPRECATE;_CRT_NONSTDC_NO_DEPRECATE;OPT_GENERIC"
 				RuntimeLibrary="2"
 				UsePrecompiledHeader="0"
 				WarningLevel="4"