diff --git a/tests/pos/i6003.scala b/tests/pos/i6003.scala
new file mode 100644
index 000000000000..6a9c105af075
--- /dev/null
+++ b/tests/pos/i6003.scala
@@ -0,0 +1,12 @@
+object Test {
+  opaque type T = String
+  object T {
+    def unwrap(t: T): String = t
+  }
+
+  opaque type U = String
+  type W = U
+  object U {
+    def unwrap(w: W): String = w: U
+  }
+}
\ No newline at end of file