diff --git a/src/attribute.ts b/src/attribute.ts
index 9a933b3b..f445259c 100644
--- a/src/attribute.ts
+++ b/src/attribute.ts
@@ -5,7 +5,7 @@
  */
 function addAttribute (element: Array<HTMLElement>|HTMLElement, attribute:string, value:string) {
   if (element instanceof Array) {
-    for (var i = 0; i < element.length; ++i) {
+    for (let i = 0; i < element.length; ++i) {
       addAttribute(element[i], attribute, value)
     }
     return
@@ -18,7 +18,7 @@ function addAttribute (element: Array<HTMLElement>|HTMLElement, attribute:string
  */
 function removeAttribute (element: Array<HTMLElement>|HTMLElement, attribute:string) {
   if (element instanceof Array) {
-    for (var i = 0; i < element.length; ++i) {
+    for (let i = 0; i < element.length; ++i) {
       removeAttribute(element[i], attribute)
     }
     return
diff --git a/src/eventListener.ts b/src/eventListener.ts
index fb08d326..ca8cdc1d 100644
--- a/src/eventListener.ts
+++ b/src/eventListener.ts
@@ -6,7 +6,7 @@ import store from './store'
  */
 function addEventListener (element: Array<HTMLElement>|HTMLElement, eventName:string, callback: () => void) {
   if (element instanceof Array) {
-    for (var i = 0; i < element.length; ++i) {
+    for (let i = 0; i < element.length; ++i) {
       addEventListener(element[i], eventName, callback)
     }
     return
@@ -20,7 +20,7 @@ function addEventListener (element: Array<HTMLElement>|HTMLElement, eventName:st
  */
 function removeEventListener (element: Array<HTMLElement>|HTMLElement, eventName: string) {
   if (element instanceof Array) {
-    for (var i = 0; i < element.length; ++i) {
+    for (let i = 0; i < element.length; ++i) {
       removeEventListener(element[i], eventName)
     }
     return