diff --git a/compiler/src/dotty/tools/dotc/ast/TreeTypeMap.scala b/compiler/src/dotty/tools/dotc/ast/TreeTypeMap.scala
index d3b231788287..98d9a0ca85f6 100644
--- a/compiler/src/dotty/tools/dotc/ast/TreeTypeMap.scala
+++ b/compiler/src/dotty/tools/dotc/ast/TreeTypeMap.scala
@@ -68,12 +68,12 @@ class TreeTypeMap(
     }
   }
 
-  val mapType: Type => Type =
+  def mapType(tp: Type): Type =
     val substMap = new TypeMap():
       def apply(tp: Type): Type = tp match
         case tp: TermRef if tp.symbol.isImport => mapOver(tp)
         case tp => tp.substSym(substFrom, substTo)
-    typeMap.andThen(substMap).andThen(mapOwnerThis)
+    mapOwnerThis(substMap(typeMap(tp)))
   end mapType
 
   private def updateDecls(prevStats: List[Tree], newStats: List[Tree]): Unit =