diff --git a/project.json b/project.json
index b1b628c..b69a50c 100644
--- a/project.json
+++ b/project.json
@@ -3,15 +3,15 @@
   "runner": "com.bartlomiejpluta.demo.runner.DemoRunner",
   "maps": [{
     "uid": "d1b85d85-c52a-46f5-b81e-444847f8ddae",
-    "source": "d1b85d85-c52a-46f5-b81e-444847f8ddae.json",
+    "source": "d1b85d85-c52a-46f5-b81e-444847f8ddae.dat",
     "name": "Hero Home"
   }, {
     "uid": "b602601a-e9b0-44bf-bc0d-5f31c9964ba1",
-    "source": "b602601a-e9b0-44bf-bc0d-5f31c9964ba1.json",
+    "source": "b602601a-e9b0-44bf-bc0d-5f31c9964ba1.dat",
     "name": "Hero House"
   }, {
     "uid": "8fbb151f-682a-4357-ba92-157e4097898f",
-    "source": "8fbb151f-682a-4357-ba92-157e4097898f.json",
+    "source": "8fbb151f-682a-4357-ba92-157e4097898f.dat",
     "name": "Forrest"
   }],
   "tileSets": [{