diff --git a/lib/string.c b/lib/string.c
index d7a5ff9..037a48a 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -488,7 +488,8 @@
  */
 void *memmove(void *dest, const void *src, size_t count)
 {
-	char *tmp, *s;
+	char *tmp;
+	const char *s;
 
 	if (dest <= src) {
 		tmp = dest;