diff --git a/dlls/msvcrt/misc.c b/dlls/msvcrt/misc.c
index bee269ed5f8..17b83069f94 100644
--- a/dlls/msvcrt/misc.c
+++ b/dlls/msvcrt/misc.c
@@ -490,7 +490,7 @@ unsigned short CDECL _byteswap_ushort(unsigned short s)
 /*********************************************************************
  * _byteswap_ulong (MSVCR80.@)
  */
-ULONG CDECL _byteswap_ulong(ULONG l)
+__msvcrt_ulong CDECL _byteswap_ulong(__msvcrt_ulong l)
 {
     return (l<<24) + ((l<<8)&0xFF0000) + ((l>>8)&0xFF00) + (l>>24);
 }
diff --git a/include/msvcrt/stdlib.h b/include/msvcrt/stdlib.h
index 287e4030669..7a2a774dfb5 100644
--- a/include/msvcrt/stdlib.h
+++ b/include/msvcrt/stdlib.h
@@ -153,6 +153,9 @@ _ACRTIMP __int64       __cdecl _atoi64(const char*);
 _ACRTIMP long double   __cdecl _atold(const char*);
 _ACRTIMP int           __cdecl _atoldbl(_LDOUBLE*,char*);
 _ACRTIMP void          __cdecl _beep(unsigned int,unsigned int);
+_ACRTIMP unsigned short   __cdecl _byteswap_ushort(unsigned short);
+_ACRTIMP __msvcrt_ulong   __cdecl _byteswap_ulong(__msvcrt_ulong);
+_ACRTIMP unsigned __int64 __cdecl _byteswap_uint64(unsigned __int64);
 _ACRTIMP char*         __cdecl _ecvt(double,int,int*,int*);
 _ACRTIMP char*         __cdecl _fcvt(double,int,int*,int*);
 _ACRTIMP char*         __cdecl _fullpath(char*,const char*,size_t);