diff --git a/Train/SimpleTrainTrack.mch b/Train/SimpleTrainTrack.mch
index 9896b709b5123d9da32f4c87beb04cc0e72671db..a1914425dc41378f80e530a24e0c9a92441ad17e 100644
--- a/Train/SimpleTrainTrack.mch
+++ b/Train/SimpleTrainTrack.mch
@@ -34,5 +34,6 @@ OPERATIONS
 DEFINITIONS
  "LibrarySVG.def"; // enable to use the external functions in the VisB json file
   OCC_TE == union(ran(%tt.(tt:occ|TTD_TrackElements(tt))));
-  FREE_TE == union(ran(%tt.(tt/:occ|TTD_TrackElements(tt))))
+  FREE_TE == union(ran(%tt.(tt/:occ|TTD_TrackElements(tt))));
+  VISB_JSON_FILE == "Track.json"
 END
\ No newline at end of file