diff --git a/tests/patmat/i12279.scala b/tests/patmat/i12279.scala
new file mode 100644
index 000000000000..5ba517757861
--- /dev/null
+++ b/tests/patmat/i12279.scala
@@ -0,0 +1,9 @@
+import scala.reflect.Typeable
+
+def unionTypeTest[T: Typeable](m: Int|T) =
+  m match
+  case x: Int => println("Got Int")
+  case t: T => println("Got T")
+
+@main def run =
+  unionTypeTest(())