diff --git a/src/js/game/shape_definition.js b/src/js/game/shape_definition.js
index 166b329d..268d9ce0 100644
--- a/src/js/game/shape_definition.js
+++ b/src/js/game/shape_definition.js
@@ -163,6 +163,10 @@ export class ShapeDefinition extends BasicSerializableObject {
                     id += "--";
                 }
             }
+
+            if (layerIndex < this.layers.length - 1) {
+                id += ":";
+            }
         }
         this.cachedHash = id;
         return id;