diff --git a/.jshintrc b/.jshintrc
index 2eecd34c..7a26e42f 100644
--- a/.jshintrc
+++ b/.jshintrc
@@ -1,27 +1,28 @@
-{
-    "globals": {
-        "phantom": false,
-        "describe": false,
-        "before": false,
-        "it": false
-    },
-    "node": true,
-    "strict": "global",
-    "expr": true,
-    "curly": false,
-    "camelcase": true,
-    "eqeqeq": false,
-    "-W041": false,
-    "-W008": false,
-    "forin": false,
-    "immed": true,
-    "multistr": true,
-    "newcap": true,
-    "nonew": true,
-    "quotmark": "single",
-    "undef": true,
-    "unused": true,
-    "loopfunc": true,
-    "trailing": true,
-    "lastsemic": true
-}
+{
+    "globals": {
+        "phantom": false,
+        "describe": false,
+        "before": false,
+        "it": false
+    },
+    "node": true,
+    "strict": "global",
+    "expr": true,
+    "curly": false,
+    "camelcase": true,
+    "eqeqeq": false,
+    "-W041": false,
+    "-W008": false,
+    "forin": false,
+    "immed": true,
+    "multistr": true,
+    "newcap": true,
+    "nonew": true,
+    "quotmark": "single",
+    "undef": true,
+    "unused": true,
+    "loopfunc": true,
+    "trailing": true,
+    "lastsemic": true,
+    "esversion": 6
+}
diff --git a/plugins/cleanupIDs.js b/plugins/cleanupIDs.js
index d250f3a7..fdad3c01 100644
--- a/plugins/cleanupIDs.js
+++ b/plugins/cleanupIDs.js
@@ -38,7 +38,6 @@ exports.fn = function(data, params) {
         currentIDstring,
         IDs = new Map(),
         referencesIDs = new Map(),
-        idPrefix = 'id-', // prefix IDs so that values like '__proto__' don't break the work
         hasStyleOrScript = false;
 
     /**