diff --git a/include/boost/config/platform/win32.hpp b/include/boost/config/platform/win32.hpp
index 39220127..6ab59f4e 100644
--- a/include/boost/config/platform/win32.hpp
+++ b/include/boost/config/platform/win32.hpp
@@ -33,7 +33,9 @@
 
 #if defined(__MINGW32__) && ((__MINGW32_MAJOR_VERSION > 2) || ((__MINGW32_MAJOR_VERSION == 2) && (__MINGW32_MINOR_VERSION >= 0)))
 #  define BOOST_HAS_STDINT_H
-#  define __STDC_LIMIT_MACROS
+#  ifndef __STDC_LIMIT_MACROS
+#     define __STDC_LIMIT_MACROS
+#  endif
 #  define BOOST_HAS_DIRENT_H
 #  define BOOST_HAS_UNISTD_H
 #endif