diff --git a/chrome/content/zotero/duplicatesMerge.js b/chrome/content/zotero/duplicatesMerge.js
index 3c0947ffe1..2e71bd7fbb 100644
--- a/chrome/content/zotero/duplicatesMerge.js
+++ b/chrome/content/zotero/duplicatesMerge.js
@@ -33,7 +33,7 @@ var Zotero_Duplicates_Pane = new function () {
 	
 	this.setItems = function (items, displayNumItemsOnTypeError) {
 		var itemTypeID, oldestItem, otherItems = [];
-		for each(var item in items) {
+		for (let item of items) {
 			// Find the oldest item
 			if (!oldestItem) {
 				oldestItem = item;
@@ -95,7 +95,7 @@ var Zotero_Duplicates_Pane = new function () {
 			}
 			
 			var numRows = 0;
-			for each(var item in _items) {
+			for (let item of items) {
 				var date = Zotero.Date.sqlToDate(item.dateAdded, true);
 				dateList.appendItem(date.toLocaleString());
 				numRows++;
diff --git a/chrome/content/zotero/xpcom/data/collections.js b/chrome/content/zotero/xpcom/data/collections.js
index 7e220e225f..cce5f51382 100644
--- a/chrome/content/zotero/xpcom/data/collections.js
+++ b/chrome/content/zotero/xpcom/data/collections.js
@@ -143,7 +143,7 @@ Zotero.Collections = function() {
 		
 		var sql = "SELECT collectionID FROM collections WHERE ";
 		var sqlParams = [];
-		for each(var id in itemIDs) {
+		for (let id of itemIDs) {
 			sql += "collectionID IN (SELECT collectionID FROM collectionItems "
 				+ "WHERE itemID=?) AND "
 			sqlParams.push(id);
diff --git a/chrome/content/zotero/xpcom/duplicates.js b/chrome/content/zotero/xpcom/duplicates.js
index 6c17eaff07..d0a066e10f 100644
--- a/chrome/content/zotero/xpcom/duplicates.js
+++ b/chrome/content/zotero/xpcom/duplicates.js
@@ -473,7 +473,8 @@ Zotero.DisjointSetForest.prototype.sameSet = function (x, y) {
 
 Zotero.DisjointSetForest.prototype.findAll = function (asIDs) {
 	var objects = [];
-	for each(var obj in this._objects) {
+	for (let i in this._objects) {
+		let obj = this._objects[i];
 		objects.push(asIDs ? obj.id : obj);
 	}
 	return objects;
@@ -483,7 +484,8 @@ Zotero.DisjointSetForest.prototype.findAll = function (asIDs) {
 Zotero.DisjointSetForest.prototype.findAllInSet = function (x, asIDs) {
 	var xRoot = this.find(x);
 	var objects = [];
-	for each(var obj in this._objects) {
+	for (let i in this._objects) {
+		let obj = this._objects[i];
 		if (this.find(obj) == xRoot) {
 			objects.push(asIDs ? obj.id : obj);
 		}
diff --git a/chrome/content/zotero/xpcom/translation/translate_item.js b/chrome/content/zotero/xpcom/translation/translate_item.js
index 0c3084d4ea..552867bdbd 100644
--- a/chrome/content/zotero/xpcom/translation/translate_item.js
+++ b/chrome/content/zotero/xpcom/translation/translate_item.js
@@ -871,7 +871,7 @@ Zotero.Translate.ItemGetter.prototype = {
 				// get attachments, although only urls will be passed if exportFileData is off
 				returnItemArray.attachments = [];
 				var attachments = returnItem.getAttachments();
-				for each(var attachmentID in attachments) {
+				for (let attachmentID of attachments) {
 					var attachment = Zotero.Items.get(attachmentID);
 					var attachmentInfo = this._attachmentToArray(attachment);