diff --git a/dlls/msvcrt/file.c b/dlls/msvcrt/file.c
index 2da5e2655e3..6671f2fc0e6 100644
--- a/dlls/msvcrt/file.c
+++ b/dlls/msvcrt/file.c
@@ -2925,7 +2925,7 @@ int CDECL MSVCRT_fgetpos(MSVCRT_FILE* file, MSVCRT_fpos_t *pos)
  */
 int CDECL MSVCRT_fputs(const char *s, MSVCRT_FILE* file)
 {
-    size_t i, len = strlen(s);
+    MSVCRT_size_t i, len = strlen(s);
     if (!(MSVCRT_fdesc[file->_file].wxflag & WX_TEXT))
       return MSVCRT_fwrite(s,sizeof(*s),len,file) == len ? 0 : MSVCRT_EOF;
     for (i=0; i<len; i++)
@@ -2939,7 +2939,7 @@ int CDECL MSVCRT_fputs(const char *s, MSVCRT_FILE* file)
  */
 int CDECL MSVCRT_fputws(const MSVCRT_wchar_t *s, MSVCRT_FILE* file)
 {
-    size_t i, len = strlenW(s);
+    MSVCRT_size_t i, len = strlenW(s);
     if (!(MSVCRT_fdesc[file->_file].wxflag & WX_TEXT))
       return MSVCRT_fwrite(s,sizeof(*s),len,file) == len ? 0 : MSVCRT_EOF;
     for (i=0; i<len; i++)
@@ -3027,7 +3027,7 @@ int CDECL MSVCRT_putchar(int c)
  */
 int CDECL MSVCRT_puts(const char *s)
 {
-    size_t len = strlen(s);
+    MSVCRT_size_t len = strlen(s);
     if (MSVCRT_fwrite(s,sizeof(*s),len,MSVCRT_stdout) != len) return MSVCRT_EOF;
     return MSVCRT_fwrite("\n",1,1,MSVCRT_stdout) == 1 ? 0 : MSVCRT_EOF;
 }
@@ -3038,7 +3038,7 @@ int CDECL MSVCRT_puts(const char *s)
 int CDECL _putws(const MSVCRT_wchar_t *s)
 {
     static const MSVCRT_wchar_t nl = '\n';
-    size_t len = strlenW(s);
+    MSVCRT_size_t len = strlenW(s);
     if (MSVCRT_fwrite(s,sizeof(*s),len,MSVCRT_stdout) != len) return MSVCRT_EOF;
     return MSVCRT_fwrite(&nl,sizeof(nl),1,MSVCRT_stdout) == 1 ? 0 : MSVCRT_EOF;
 }
diff --git a/dlls/msvcrt/mbcs.c b/dlls/msvcrt/mbcs.c
index a6e0ccac2e6..f738bcfe510 100644
--- a/dlls/msvcrt/mbcs.c
+++ b/dlls/msvcrt/mbcs.c
@@ -74,12 +74,12 @@ static MSVCRT_wchar_t msvcrt_mbc_to_wc(unsigned int ch)
   return chW;
 }
 
-static inline size_t u_strlen( const unsigned char *str )
+static inline MSVCRT_size_t u_strlen( const unsigned char *str )
 {
   return strlen( (const char*) str );
 }
 
-static inline unsigned char* u_strncat( unsigned char* dst, const unsigned char* src, size_t len )
+static inline unsigned char* u_strncat( unsigned char* dst, const unsigned char* src, MSVCRT_size_t len )
 {
   return (unsigned char*)strncat( (char*)dst, (const char*)src, len);
 }
@@ -94,12 +94,12 @@ static inline int u_strcasecmp( const unsigned char *s1, const unsigned char *s2
   return strcasecmp( (const char*)s1, (const char*)s2 );
 }
 
-static inline int u_strncmp( const unsigned char *s1, const unsigned char *s2, size_t len )
+static inline int u_strncmp( const unsigned char *s1, const unsigned char *s2, MSVCRT_size_t len )
 {
   return strncmp( (const char*)s1, (const char*)s2, len );
 }
 
-static inline int u_strncasecmp( const unsigned char *s1, const unsigned char *s2, size_t len )
+static inline int u_strncasecmp( const unsigned char *s1, const unsigned char *s2, MSVCRT_size_t len )
 {
   return strncasecmp( (const char*)s1, (const char*)s2, len );
 }
@@ -124,12 +124,12 @@ static inline unsigned char *u__strset( unsigned char *s, unsigned char c )
   return (unsigned char*) _strset( (char*)s, c);
 }
 
-static inline unsigned char *u__strnset( unsigned char *s, unsigned char c, size_t len )
+static inline unsigned char *u__strnset( unsigned char *s, unsigned char c, MSVCRT_size_t len )
 {
   return (unsigned char*) _strnset( (char*)s, c, len );
 }
 
-static inline size_t u_strcspn( const unsigned char *s, const unsigned char *rej )
+static inline MSVCRT_size_t u_strcspn( const unsigned char *s, const unsigned char *rej )
 {
   return strcspn( (const char *)s, (const char*)rej );
 }