diff --git a/dlls/msvcrt/ctype.c b/dlls/msvcrt/ctype.c
index 9e2d029950e..7322ea47c28 100644
--- a/dlls/msvcrt/ctype.c
+++ b/dlls/msvcrt/ctype.c
@@ -425,8 +425,7 @@ int CDECL MSVCRT__toupper(int c)
 int CDECL MSVCRT__tolower_l(int c, MSVCRT__locale_t locale)
 {
     MSVCRT_pthreadlocinfo locinfo;
-    unsigned char str[2], *p = str;
-    WCHAR wide, lower;
+    unsigned char str[2], *p = str, ret[2];
 
     if(!locale)
         locinfo = get_locinfo();
@@ -444,22 +443,15 @@ int CDECL MSVCRT__tolower_l(int c, MSVCRT__locale_t locale)
     }
     *p++ = c & 255;
 
-    if(!MultiByteToWideChar(locinfo->lc_codepage,
-                MB_ERR_INVALID_CHARS, (char*)str, p-str, &wide, 1))
-        return c;
-
-    lower = tolowerW(wide);
-    if(lower == wide)
-        return str[0] + (str[1]<<8);
-
-    switch(WideCharToMultiByte(locinfo->lc_codepage, 0,
-                &lower, 1, (char*)str, 2, NULL, NULL)) {
+    switch(__crtLCMapStringA(locinfo->lc_handle[MSVCRT_LC_CTYPE], LCMAP_LOWERCASE,
+                (char*)str, p-str, (char*)ret, 2, locinfo->lc_codepage, 0))
+    {
     case 0:
         return c;
     case 1:
-        return str[0];
+        return ret[0];
     default:
-        return str[0] + (str[1]<<8);
+        return ret[0] + (ret[1]<<8);
     }
 }
 
diff --git a/dlls/msvcrt/msvcrt.h b/dlls/msvcrt/msvcrt.h
index ef1154ce76b..cc4541cceef 100644
--- a/dlls/msvcrt/msvcrt.h
+++ b/dlls/msvcrt/msvcrt.h
@@ -1130,6 +1130,7 @@ void __cdecl MSVCRT__free_locale(MSVCRT__locale_t);
 void free_locinfo(MSVCRT_pthreadlocinfo) DECLSPEC_HIDDEN;
 void free_mbcinfo(MSVCRT_pthreadmbcinfo) DECLSPEC_HIDDEN;
 int _setmbcp_l(int, LCID, MSVCRT_pthreadmbcinfo) DECLSPEC_HIDDEN;
+int __cdecl __crtLCMapStringA(LCID, DWORD, const char*, int, char*, int, unsigned int, int) DECLSPEC_HIDDEN;
 
 #ifndef __WINE_MSVCRT_TEST
 int            __cdecl MSVCRT__write(int,const void*,unsigned int);