diff --git a/src/playlist/sort.c b/src/playlist/sort.c
index 1b6d1b6807e568f9bcd6ef5b1bb17dd8c7fa0f19..588bd35ab5505e19fa2a4463436e12dc18306faa 100644
--- a/src/playlist/sort.c
+++ b/src/playlist/sort.c
@@ -193,6 +193,8 @@ static int recursiveNodeSort( playlist_t *p_playlist, playlist_item_t *p_node,
 int playlist_RecursiveNodeSort( playlist_t *p_playlist, playlist_item_t *p_node,
                                 int i_mode, int i_type )
 {
+    PL_ASSERT_LOCKED;
+
     /* Ask the playlist to reset as we are changing the order */
     pl_priv(p_playlist)->b_reset_currently_playing = true;