diff --git a/lib/internal/socket_list.js b/lib/internal/socket_list.js
index d12686e1de107d..8cd7b1e0ed9057 100644
--- a/lib/internal/socket_list.js
+++ b/lib/internal/socket_list.js
@@ -47,7 +47,7 @@ class SocketListSend extends EventEmitter {
     this._request({
       cmd: 'NODE_SOCKET_GET_COUNT',
       key: this.key
-    }, 'NODE_SOCKET_COUNT', false, function(err, msg) {
+    }, 'NODE_SOCKET_COUNT', false, (err, msg) => {
       if (err) return callback(err);
       callback(null, msg.count);
     });