diff --git a/.eslintrc.js b/.eslintrc.js
index b62b93d8ba..855c45f454 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -76,7 +76,8 @@ module.exports = {
         sourceType: 'module'
       },
       env: {
-        browser: true,
+        // do not access global window properties without going through window
+        browser: false,
         es6: true
       },
       globals: {
@@ -95,7 +96,9 @@ module.exports = {
       parserOptions: {
         sourceType: 'module'
       },
-      env: {},
+      env: {
+        browser: false
+      },
       globals: {},
       rules: {
         'func-names': [2, 'as-needed'],
@@ -103,6 +106,19 @@ module.exports = {
         'no-use-before-define': 'off'
       }
     },
+    {
+      // polyfills are mostly copy-pasted from sources so we don't control their styling
+      files: ['lib/core/utils/pollyfills.js'],
+      env: {
+        browser: false
+      },
+      rules: {
+        'func-names': 0,
+        'no-bitwise': 0,
+        curly: 0,
+        eqeqeq: 0
+      }
+    },
     {
       files: ['test/act-rules/**/*.js', 'test/aria-practices/**/*.js'],
       env: {
diff --git a/lib/commons/color/get-background-stack.js b/lib/commons/color/get-background-stack.js
index a37833eb9f..87225e2b5d 100644
--- a/lib/commons/color/get-background-stack.js
+++ b/lib/commons/color/get-background-stack.js
@@ -12,7 +12,7 @@ import reduceToElementsBelowFloating from '../dom/reduce-to-elements-below-float
  * @return {Boolean}
  */
 function isInlineDescendant(node, descendant) {
-  const CONTAINED_BY = Node.DOCUMENT_POSITION_CONTAINED_BY;
+  const CONTAINED_BY = window.Node.DOCUMENT_POSITION_CONTAINED_BY;
   // eslint-disable-next-line no-bitwise
   if (!(node.compareDocumentPosition(descendant) & CONTAINED_BY)) {
     return false;
diff --git a/lib/core/utils/dq-element.js b/lib/core/utils/dq-element.js
index 4e5d0ffc28..db1c5f65bb 100644
--- a/lib/core/utils/dq-element.js
+++ b/lib/core/utils/dq-element.js
@@ -20,8 +20,8 @@ function getSource(element) {
     return '';
   }
   var source = element.outerHTML;
-  if (!source && typeof XMLSerializer === 'function') {
-    source = new XMLSerializer().serializeToString(element);
+  if (!source && typeof window.XMLSerializer === 'function') {
+    source = new window.XMLSerializer().serializeToString(element);
   }
   return truncate(source || '');
 }
diff --git a/lib/core/utils/parse-crossorigin-stylesheet.js b/lib/core/utils/parse-crossorigin-stylesheet.js
index 1a504216ba..3ec44fa526 100644
--- a/lib/core/utils/parse-crossorigin-stylesheet.js
+++ b/lib/core/utils/parse-crossorigin-stylesheet.js
@@ -26,7 +26,7 @@ function parseCrossOriginStylesheet(
   importedUrls.push(url);
 
   return new Promise((resolve, reject) => {
-    const request = new XMLHttpRequest();
+    const request = new window.XMLHttpRequest();
     request.open('GET', url);
 
     request.timeout = constants.preload.timeout;
diff --git a/lib/core/utils/pollyfills.js b/lib/core/utils/pollyfills.js
index fe1de7f354..6829b80dc8 100644
--- a/lib/core/utils/pollyfills.js
+++ b/lib/core/utils/pollyfills.js
@@ -1,4 +1,3 @@
-/* eslint-disable */
 /*
  These polyfills came directly from the ES Specification itself
  Contained within:
@@ -348,8 +347,8 @@ if (!Array.prototype.flat) {
 
 // linked from MDN docs on isConnected
 // @see https://gist.github.com/eligrey/f109a6d0bf4efe3461201c3d7b745e8f
-if (window.Node && !('isConnected' in Node.prototype)) {
-  Object.defineProperty(Node.prototype, 'isConnected', {
+if (window.Node && !('isConnected' in window.Node.prototype)) {
+  Object.defineProperty(window.Node.prototype, 'isConnected', {
     get() {
       return (
         !this.ownerDocument ||