diff --git a/ext/mbstring/libmbfl/config.h.w32 b/ext/mbstring/libmbfl/config.h.w32
index bb76dfe8276de..6d05bfc67c363 100644
--- a/ext/mbstring/libmbfl/config.h.w32
+++ b/ext/mbstring/libmbfl/config.h.w32
@@ -1,6 +1 @@
-/* #undef HAVE_STRINGS_H */
-/* #undef HAVE_STRCASECMP */
 #define HAVE_STRICMP 1
-#define HAVE_WIN32_NATIVE_THREAD 1
-#define USE_WIN32_NATIVE_THREAD 1
-#define ENABLE_THREADS 1