diff --git a/src/Kernel/Behavior.class.st b/src/Kernel/Behavior.class.st
index 65cdad8ecdd..5b4698a71f1 100644
--- a/src/Kernel/Behavior.class.st
+++ b/src/Kernel/Behavior.class.st
@@ -8,7 +8,8 @@ Class {
 		'superclass',
 		'methodDict',
 		'format',
-		'layout'
+		'layout',
+		'lookupMethodDict'
 	],
 	#classVars : [
 		'ClassProperties',