diff --git a/dedupe.js b/dedupe.js
index c5af21d..c28e241 100644
--- a/dedupe.js
+++ b/dedupe.js
@@ -70,7 +70,7 @@ const classNames = (function () {
 		// https://github.com/petkaantonov/bluebird/wiki/Optimization-killers#32-leaking-arguments
 		const length = arguments.length;
 		const args = Array(len);
-		for (const i = 0; i < length; i++) {
+		for (let i = 0; i < length; i++) {
 			args[i] = arguments[i];
 		}