diff --git a/pattern.c b/pattern.c
index 68862df..1342cb6 100644
--- a/pattern.c
+++ b/pattern.c
@@ -1738,6 +1738,7 @@ static game_drawstate *game_new_drawstate(drawing *dr, const game_state *state)
 static void game_free_drawstate(drawing *dr, game_drawstate *ds)
 {
     sfree(ds->visible);
+    sfree(ds->numcolours);
     sfree(ds->strbuf);
     sfree(ds);
 }