diff --git a/sdk/lib/crt/mbstring/mbscmp.c b/sdk/lib/crt/mbstring/mbscmp.c
index 611d086cc45..8f93a5fc838 100644
--- a/sdk/lib/crt/mbstring/mbscmp.c
+++ b/sdk/lib/crt/mbstring/mbscmp.c
@@ -1,10 +1,14 @@
 #include <mbstring.h>
 #include <string.h>
+#include <precomp.h>
 
 /*
  * @implemented
  */
 int _mbscmp(const unsigned char *str1, const unsigned char *str2)
 {
+    if (!MSVCRT_CHECK_PMT(str1 && str2))
+        return _NLSCMPERROR;
+
   return strcmp((const char*)str1, (char*)str2);
 }