diff --git a/mux_test.go b/mux_test.go
index f5c1e9c5..34c00dd2 100644
--- a/mux_test.go
+++ b/mux_test.go
@@ -1943,7 +1943,7 @@ type TestA301ResponseWriter struct {
 }
 
 func (ho *TestA301ResponseWriter) Header() http.Header {
-	return http.Header(ho.hh)
+	return ho.hh
 }
 
 func (ho *TestA301ResponseWriter) Write(b []byte) (int, error) {