diff --git "a/sdk/lib/crt/mbstring/mbsncat.c" "b/sdk/lib/crt/mbstring/mbsncat.c"
index 21e63d0c0a1..db07a83e7b5 100644
--- "a/sdk/lib/crt/mbstring/mbsncat.c"
+++ "b/sdk/lib/crt/mbstring/mbsncat.c"
@@ -51,7 +51,7 @@ unsigned char * _mbsnbcat(unsigned char *dst, const unsigned char *src, size_t n
 	if (n != 0) {
 		d = dst + _mbslen(dst); // get the end of string
 		d += _mbclen2(*d); // move 1 or 2 up
-
+#if 0
 		do {
 			if ((*d++ = *s++) == 0)
 			{
@@ -62,6 +62,14 @@ unsigned char * _mbsnbcat(unsigned char *dst, const unsigned char *src, size_t n
 			if ( !(n==1 && _ismbblead(*s)) )
 				n--;
 		} while (n > 0);
+#endif
+      while (*src && n--)
+      {
+        d--;      // Back up from the ending NULL
+        *d = *s;  // Copy one character
+        d++;      // Point to just past the copied char
+        *d = 0;   // Put back then ending NULL
+      }
 	}
 	return dst;
 }