diff --git a/compiler/src/dotty/tools/dotc/ast/tpd.scala b/compiler/src/dotty/tools/dotc/ast/tpd.scala
index acffb1e89972..6f54f342dcb2 100644
--- a/compiler/src/dotty/tools/dotc/ast/tpd.scala
+++ b/compiler/src/dotty/tools/dotc/ast/tpd.scala
@@ -414,7 +414,7 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
       case pre: ThisType =>
         tp.isType ||
         pre.cls.isStaticOwner ||
-        tp.symbol.isParamOrAccessor && !pre.cls.is(Trait) && ctx.owner.enclosingClass == pre.cls
+        tp.symbol.isParamOrAccessor && !pre.cls.is(Trait) && !tp.symbol.owner.is(Trait) && ctx.owner.enclosingClass == pre.cls
           // was ctx.owner.enclosingClass.derivesFrom(pre.cls) which was not tight enough
           // and was spuriously triggered in case inner class would inherit from outer one
           // eg anonymous TypeMap inside TypeMap.andThen
diff --git a/tests/pos/i18091.scala b/tests/pos/i18091.scala
new file mode 100644
index 000000000000..ef896cedb751
--- /dev/null
+++ b/tests/pos/i18091.scala
@@ -0,0 +1,5 @@
+trait B(val y: Int)
+
+class C extends B(20)  {
+  def foo(): Unit = println(y)
+}
\ No newline at end of file