diff --git a/panda/src/express/typeRegistryNode.cxx b/panda/src/express/typeRegistryNode.cxx
index edcc5f41d5..92925388d2 100644
--- a/panda/src/express/typeRegistryNode.cxx
+++ b/panda/src/express/typeRegistryNode.cxx
@@ -21,7 +21,7 @@
 #include <algorithm>
 
 // Define this to double-check all the inheritance derivations.
-//#define PARANOID_INHERITANCE
+#define PARANOID_INHERITANCE
 
 ////////////////////////////////////////////////////////////////////
 //     Function: TypeRegistryNode::Constructor