diff --git a/src/Refinements/TC.class.st b/src/Refinements/TC.class.st
index 78eebd744..ddf132c06 100644
--- a/src/Refinements/TC.class.st
+++ b/src/Refinements/TC.class.st
@@ -24,7 +24,7 @@ TC >> apply: ts [
 	monoSymbol :=
 		'(',
 		symbol,
-		(ts inject: '' into: [ :soFar :thisArgType | ' ', thisArgType printString ]),
+		(ts inject: '' into: [ :soFar :thisArgType | ' ', thisArgType unsafeName ]),
 		')'.
 	^TC symbol: monoSymbol
 ]