diff --git a/compiler/src/dotty/tools/dotc/transform/AugmentScala2Traits.scala b/compiler/src/dotty/tools/dotc/transform/AugmentScala2Traits.scala
index a1a9f498bebe..d7280624757e 100644
--- a/compiler/src/dotty/tools/dotc/transform/AugmentScala2Traits.scala
+++ b/compiler/src/dotty/tools/dotc/transform/AugmentScala2Traits.scala
@@ -65,5 +65,6 @@ class AugmentScala2Traits extends MiniPhase with IdentityDenotTransformer { this
         sym.ensureNotPrivate.installAfter(thisPhase)
     }
     mixin.setFlag(Scala2xPartiallyAugmented)
+    mixin.transformAfter(thisPhase, d => { d.setFlag(Scala2xPartiallyAugmented); d })
   }
 }
diff --git a/tests/run/i8101/Foo.scala b/tests/run/i8101/Foo.scala
new file mode 100644
index 000000000000..79c2be3f8a7a
--- /dev/null
+++ b/tests/run/i8101/Foo.scala
@@ -0,0 +1,3 @@
+trait Foo {
+  def f: String = ???
+}
\ No newline at end of file
diff --git a/tests/run/i8101/JavaFoo.java b/tests/run/i8101/JavaFoo.java
new file mode 100644
index 000000000000..d14bb5b3ef4c
--- /dev/null
+++ b/tests/run/i8101/JavaFoo.java
@@ -0,0 +1,3 @@
+public abstract class JavaFoo {
+    public abstract int read();
+}
\ No newline at end of file
diff --git a/tests/run/i8101/Test.scala b/tests/run/i8101/Test.scala
new file mode 100644
index 000000000000..8ac8bf705ad2
--- /dev/null
+++ b/tests/run/i8101/Test.scala
@@ -0,0 +1,6 @@
+class Bar extends JavaFoo with Foo {
+  def read(): Int = ???
+}
+
+@main def Test =
+  val stdout = new Bar