diff --git a/mingw-w64-headers/crt/stdlib.h b/mingw-w64-headers/crt/stdlib.h
index 6057e09..0466c90 100644
--- a/mingw-w64-headers/crt/stdlib.h
+++ b/mingw-w64-headers/crt/stdlib.h
@@ -343,7 +343,7 @@
   void __cdecl qsort(void *_Base,size_t _NumOfElements,size_t _SizeOfElements,int (__cdecl *_PtFuncCompare)(const void *,const void *));
 #endif
   unsigned short __cdecl _byteswap_ushort(unsigned short _Short);
-  /*unsigned long __cdecl _byteswap_ulong (unsigned long _Long); */
+  unsigned long __cdecl _byteswap_ulong (unsigned long _Long);
   __MINGW_EXTENSION unsigned __int64 __cdecl _byteswap_uint64(unsigned __int64 _Int64);
   div_t __cdecl div(int _Numerator,int _Denominator);
   char *__cdecl getenv(const char *_VarName) __MINGW_ATTRIB_DEPRECATED_SEC_WARN;