diff --git a/index.js b/index.js
index 114a4fd..9c591b4 100644
--- a/index.js
+++ b/index.js
@@ -235,7 +235,7 @@ class API {
   }
 
   async close() {
-    await util.promisify(this.server.close).bind(this.server);
+    await util.promisify(this.server.close).bind(this.server)();
   }
 }