diff --git a/CHANGELOG b/CHANGELOG
index afcc567..08634e7 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -34,6 +34,7 @@ xx/xx/2018 autofs-5.1.5
 - add master map pseudo options for mount propagation.
 - fix age setting at startup.
 - fix use after free in parse_ldap_config().
+- fix incorrect locking in sss lookup.
 
 19/12/2017 autofs-5.1.4
 - fix spec file url.
diff --git a/modules/lookup_sss.c b/modules/lookup_sss.c
index 88ec169..7859830 100644
--- a/modules/lookup_sss.c
+++ b/modules/lookup_sss.c
@@ -786,9 +786,9 @@ int lookup_mount(struct autofs_point *ap, const char *name, int name_len, void *
 	 * when we're starting up so just take the readlock in that
 	 */
 	if (ap->flags & MOUNT_FLAG_REMOUNT)
-		cache_writelock(mc);
-	else
 		cache_readlock(mc);
+	else
+		cache_writelock(mc);
 	me = cache_lookup(mc, key);
 	/* Stale mapent => check for entry in alternate source or wildcard */
 	if (me && !me->mapent) {