diff --git a/src/locker.js b/src/locker.js
index 8f817c6b6..6d6f511b0 100644
--- a/src/locker.js
+++ b/src/locker.js
@@ -24,7 +24,7 @@ Locker.prototype.lock = function (operation) {
     assert.strictEqual(typeof operation, 'string');
 
     if (this._operation !== null) {
-        let error = new BoxError(BoxError.CONFLICT, `Locked for ${this._operation}`);
+        const error = new BoxError(BoxError.CONFLICT, `Locked for ${this._operation}`);
         error.operation = this._operation;
         return error;
     }