diff --git a/lib/node/config.js b/lib/node/config.js
index dac2c469..2a77b759 100644
--- a/lib/node/config.js
+++ b/lib/node/config.js
@@ -704,6 +704,8 @@ Config.prototype.parseConfig = function parseConfig(text) {
  */
 
 Config.prototype.parseArg = function parseArg(argv) {
+  let key;
+
   if (!argv || typeof argv !== 'object')
     argv = process.argv;
 
@@ -711,7 +713,7 @@ Config.prototype.parseArg = function parseArg(argv) {
 
   for (let i = 2; i < argv.length; i++) {
     let arg = argv[i];
-    let key, value, alias, equals;
+    let value, alias, equals;
 
     assert(typeof arg === 'string');