diff --git a/src/Refactoring-Core/RBCondition.class.st b/src/Refactoring-Core/RBCondition.class.st
index 356359b18b3..13a90b7620e 100644
--- a/src/Refactoring-Core/RBCondition.class.st
+++ b/src/Refactoring-Core/RBCondition.class.st
@@ -200,7 +200,7 @@ RBCondition class >> hierarchyOf: aClass canUnderstand: aSelector [
 	^self new
 		type: (Array with: #hierarchyUnderstandsSelector with: aClass with: aSelector)
 		block: [aClass hierarchyDefinesMethod: aSelector]
-		errorString: aClass printString , ' <1?or a subclass:and all subclasses do not> understand<1?s:> ' , aSelector printString
+		errorString: aClass printString , ' <1? and/or part of it''s Hierarchy already: and/or part of it''s Hierarchy do not> understand<1?s:> ' , aSelector printString
 ]
 
 { #category : #'instance creation' }
diff --git a/src/Refactoring-Core/RBRenameMethodRefactoring.class.st b/src/Refactoring-Core/RBRenameMethodRefactoring.class.st
index e3381a2ef5d..d1b50876c67 100644
--- a/src/Refactoring-Core/RBRenameMethodRefactoring.class.st
+++ b/src/Refactoring-Core/RBRenameMethodRefactoring.class.st
@@ -74,8 +74,8 @@ RBRenameMethodRefactoring >> parseTreeRewriter [
 RBRenameMethodRefactoring >> preconditions [
 	| newCondition |
 	newCondition := (RBCondition 
-							withBlock: [newSelector = oldSelector]
-							errorString: 'The selectors are <1?:not >equivalent') 
+							withBlock: [ newSelector = oldSelector ]
+							errorString: 'The selector name has <1?not:> changed <1?:to #', newSelector, '>') 
 						& (RBCondition 
 							withBlock: [permutation asArray ~= (1 to: oldSelector numArgs) asArray]
 							errorString: 'The arguments are <1?:not >permuted').