diff --git a/src/System-Changes/ChangeSet.class.st b/src/System-Changes/ChangeSet.class.st
index f501413f2d9..84accc83ff9 100644
--- a/src/System-Changes/ChangeSet.class.st
+++ b/src/System-Changes/ChangeSet.class.st
@@ -800,7 +800,8 @@ ChangeSet >> expungeEmptyClassChangeEntries [
 ChangeSet >> fatDefForClass: class [ 
 	| newDef oldDef oldStrm newStrm outStrm oldVars newVars addedVars |
 	class isBehavior ifFalse: [ ^ class definition ].
-	newDef := class definition.
+	
+	newDef := class oldDefinition.
 	oldDef := (self changeRecorderFor: class) priorDefinition.
 	oldDef ifNil: [ ^ newDef ].
 	oldDef = newDef ifTrue: [ ^ newDef ].
diff --git a/src/Tests/ChangeSetClassChangesTest.class.st b/src/Tests/ChangeSetClassChangesTest.class.st
index 697cd992f11..6f722d6e730 100644
--- a/src/Tests/ChangeSetClassChangesTest.class.st
+++ b/src/Tests/ChangeSetClassChangesTest.class.st
@@ -165,7 +165,7 @@ ChangeSetClassChangesTest >> testChangeClassCategory [
 		classVariableNames: ''
 		poolDictionaries: ''
 		category: 'DeleteMe-1'.
-	saveClassDefinition := (Smalltalk globals classNamed: #JunkClass) definition.
+	saveClassDefinition := (Smalltalk globals classNamed: #JunkClass) oldDefinition.
 	self assert: saveClassDefinition = (ChangeSet current fatDefForClass: (Smalltalk globals classNamed: #JunkClass)).	"Redefine the class, changing only the class category"
 	Object
 		subclass: #JunkClass
@@ -182,7 +182,7 @@ ChangeSetClassChangesTest >> testChangeClassCategory [
 	self
 		assert:
 			(self
-				isDefinition: (Smalltalk globals classNamed: #JunkClass) definition
+				isDefinition: (Smalltalk globals classNamed: #JunkClass) oldDefinition
 				equivalentTo: (ChangeSet current fatDefForClass: (Smalltalk globals classNamed: #JunkClass))).	"Assert that the change has been recorded in the current change set"
 	self
 		assert: