diff --git a/test/fixedbugs/bug423.go b/test/fixedbugs/bug423.go
index 882108df8b..7268912454 100644
--- a/test/fixedbugs/bug423.go
+++ b/test/fixedbugs/bug423.go
@@ -14,7 +14,7 @@ func main() {
 }
 
 func F(arg int) {
-	var X int64
+	var X interface{}
 	_ = X // used once
 	X = 0
 	X = 0