diff --git a/missing/memcmp.c b/missing/memcmp.c
index a81eec4244..9657e6c372 100644
--- a/missing/memcmp.c
+++ b/missing/memcmp.c
@@ -11,7 +11,8 @@ memcmp(const void *s1, const void *s2, size_t len)
     register int tmp;
 
     for (; len; --len) {
-	if (tmp = *a++ - *b++)
+	tmp = *a++ - *b++;
+	if (tmp)
 	    return tmp;
     }
     return 0;