diff --git "a/sdk/lib/crt/mbstring/mbsncat.c" "b/sdk/lib/crt/mbstring/mbsncat.c"
index 21e63d0c0a1..13d75985f06 100644
--- "a/sdk/lib/crt/mbstring/mbsncat.c"
+++ "b/sdk/lib/crt/mbstring/mbsncat.c"
@@ -48,6 +48,7 @@ unsigned char * _mbsnbcat(unsigned char *dst, const unsigned char *src, size_t n
 {
 	unsigned char *d;
 	const unsigned char *s = src;
+ERR("src '%c' (0x%x)\n", *s, *s);
 	if (n != 0) {
 		d = dst + _mbslen(dst); // get the end of string
 		d += _mbclen2(*d); // move 1 or 2 up