Index: nls.c
===================================================================
--- nls.c	(revision 59836)
+++ nls.c	(working copy)
@@ -1464,7 +1464,7 @@
                     INT WideCharCount)
 {
     /* Check the parameters. */
-    if (MultiByteString == NULL ||
+	if (MultiByteString == NULL || MultiByteCount == 0 ||
         (WideCharString == NULL && WideCharCount > 0) ||
         (PVOID)MultiByteString == (PVOID)WideCharString)
     {
@@ -1898,7 +1898,7 @@
                     LPBOOL UsedDefaultChar)
 {
     /* Check the parameters. */
-    if (WideCharString == NULL ||
+	if (WideCharString == NULL || WideCharCount == 0 ||
         (MultiByteString == NULL && MultiByteCount > 0) ||
         (PVOID)WideCharString == (PVOID)MultiByteString ||
         MultiByteCount < 0)
@@ -1916,6 +1916,11 @@
     switch (CodePage)
     {
         case CP_UTF8:
+			if(DefaultChar != NULL || UsedDefaultChar != NULL)
+			{
+				SetLastError(ERROR_INVALID_PARAMETER);
+				return 0;
+			}
             return IntWideCharToMultiByteUTF8(CodePage,
                                               Flags,
                                               WideCharString,