diff --git a/panda/src/collide/collisionTraverser.h b/panda/src/collide/collisionTraverser.h
index 19b249cb45..fc039e3f7d 100644
--- a/panda/src/collide/collisionTraverser.h
+++ b/panda/src/collide/collisionTraverser.h
@@ -64,7 +64,7 @@ PUBLISHED:
   void clear_colliders();
   MAKE_SEQ_PROPERTY(colliders, get_num_colliders, get_collider);
 
-  void traverse(const NodePath &root);
+  BLOCKING void traverse(const NodePath &root);
 
 #if defined(DO_COLLISION_RECORDING) || !defined(CPPPARSER)
   void set_recorder(CollisionRecorder *recorder);