diff --git a/test/fixedbugs/bug509.go b/test/fixedbugs/bug509.go
new file mode 100644
index 00000000000..df6ed61f893
--- /dev/null
+++ b/test/fixedbugs/bug509.go
@@ -0,0 +1,30 @@
+// compile
+
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Gccgo mishandles a couple of alias cases.
+
+package p
+
+type S struct{}
+
+func (*S) M() {}
+
+type I interface {
+	M()
+}
+
+type A = *S
+
+var V1 I
+var _ = V1.(*S)
+var _ = V1.(A)
+
+func F() {
+	var v I
+	v = (*S)(nil)
+	v = A(nil)
+	_ = v
+}