diff --git a/command/serve.go b/command/serve.go
index 379b6c7..811e7df 100644
--- a/command/serve.go
+++ b/command/serve.go
@@ -179,6 +179,7 @@ func (ph *ProxyHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			}
 		}
 	}
+	http.Error(w, http.StatusText(http.StatusForbidden), http.StatusForbidden)
 	return
 }