diff --git a/lib/prefix.c b/lib/prefix.c
index bc6afcf9f8..84a04c5300 100644
--- a/lib/prefix.c
+++ b/lib/prefix.c
@@ -665,7 +665,7 @@ str2prefix_ipv6 (const char *str, struct prefix_ipv6 *p)
       strncpy (cp, str, pnt - str);
       *(cp + (pnt - str)) = '\0';
       ret = inet_pton (AF_INET6, cp, &p->prefix);
-      free (cp);
+      XFREE (MTYPE_TMP, cp);
       if (ret == 0)
 	return 0;
       plen = (u_char) atoi (++pnt);