diff --git a/src/lib.rs b/src/lib.rs
index 171a721..2f57150 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -66,7 +66,7 @@ pub fn add_tiles(game_data: String, image: String, prefix: String) -> String {
                 colour_id: None
             };
 
-            if tile != bitsy_parser::mock::tile_background() && !game.tiles.contains(&tile) {
+            if !game.tiles.contains(&tile) {
                 game.add_tile(tile);
 
                 tile_index += 1;
@@ -74,6 +74,7 @@ pub fn add_tiles(game_data: String, image: String, prefix: String) -> String {
         }
     }
 
+    game.dedupe_tiles();
     game.to_string()
 }