diff --git a/dlls/msvcr100/msvcr100.spec b/dlls/msvcr100/msvcr100.spec
index 42d8310899d..d732d697351 100644
--- a/dlls/msvcr100/msvcr100.spec
+++ b/dlls/msvcr100/msvcr100.spec
@@ -1318,7 +1318,7 @@
 @ cdecl _wcsupr(wstr) msvcrt._wcsupr
 @ stub _wcsupr_l
 @ cdecl _wcsupr_s(wstr long) msvcrt._wcsupr_s
-@ stub _wcsupr_s_l
+@ cdecl _wcsupr_s_l(wstr long ptr) msvcrt._wcsupr_s_l
 @ stub _wcsxfrm_l
 @ cdecl _wctime32(ptr) msvcrt._wctime32
 @ stub _wctime32_s
diff --git a/dlls/msvcr80/msvcr80.spec b/dlls/msvcr80/msvcr80.spec
index f9eaaf0e22c..1631fdb454f 100644
--- a/dlls/msvcr80/msvcr80.spec
+++ b/dlls/msvcr80/msvcr80.spec
@@ -1171,7 +1171,7 @@
 @ cdecl _wcsupr(wstr) msvcrt._wcsupr
 @ stub _wcsupr_l
 @ cdecl _wcsupr_s(wstr long) msvcrt._wcsupr_s
-@ stub _wcsupr_s_l
+@ cdecl _wcsupr_s_l(wstr long ptr) msvcrt._wcsupr_s_l
 @ stub _wcsxfrm_l
 @ cdecl _wctime32(ptr) msvcrt._wctime32
 @ stub _wctime32_s
diff --git a/dlls/msvcr90/msvcr90.spec b/dlls/msvcr90/msvcr90.spec
index b7288da5ffe..8148caf0bf5 100644
--- a/dlls/msvcr90/msvcr90.spec
+++ b/dlls/msvcr90/msvcr90.spec
@@ -1158,7 +1158,7 @@
 @ cdecl _wcsupr(wstr) msvcrt._wcsupr
 @ stub _wcsupr_l
 @ cdecl _wcsupr_s(wstr long) msvcrt._wcsupr_s
-@ stub _wcsupr_s_l
+@ cdecl _wcsupr_s_l(wstr long ptr) msvcrt._wcsupr_s_l
 @ stub _wcsxfrm_l
 @ cdecl _wctime32(ptr) msvcrt._wctime32
 @ stub _wctime32_s
diff --git a/dlls/msvcrt/wcs.c b/dlls/msvcrt/wcs.c
index d45094a53fc..93aa0f02e7d 100644
--- a/dlls/msvcrt/wcs.c
+++ b/dlls/msvcrt/wcs.c
@@ -103,10 +103,10 @@ MSVCRT_wchar_t* CDECL _wcsset( MSVCRT_wchar_t* str, MSVCRT_wchar_t c )
 }
 
 /******************************************************************
- *		_wcsupr_s (MSVCRT.@)
- *
+ *		_wcsupr_s_l (MSVCRT.@)
  */
-INT CDECL MSVCRT__wcsupr_s( MSVCRT_wchar_t* str, MSVCRT_size_t n )
+int CDECL MSVCRT__wcsupr_s_l( MSVCRT_wchar_t* str, MSVCRT_size_t n,
+   MSVCRT__locale_t locale )
 {
   MSVCRT_wchar_t* ptr = str;
 
@@ -120,6 +120,7 @@ INT CDECL MSVCRT__wcsupr_s( MSVCRT_wchar_t* str, MSVCRT_size_t n )
   while (n--)
   {
     if (!*ptr) return 0;
+    /* FIXME: add locale support */
     *ptr = toupperW(*ptr);
     ptr++;
   }
@@ -131,6 +132,15 @@ INT CDECL MSVCRT__wcsupr_s( MSVCRT_wchar_t* str, MSVCRT_size_t n )
   return MSVCRT_EINVAL;
 }
 
+/******************************************************************
+ *		_wcsupr_s (MSVCRT.@)
+ *
+ */
+INT CDECL MSVCRT__wcsupr_s( MSVCRT_wchar_t* str, MSVCRT_size_t n )
+{
+  return MSVCRT__wcsupr_s_l( str, n, NULL );
+}
+
 /******************************************************************
  *		_wcslwr_s (MSVCRT.@)
  */