diff --git a/lib/browser.js b/lib/browser.js
index c336fe87..89c521e7 100644
--- a/lib/browser.js
+++ b/lib/browser.js
@@ -1,14 +1,23 @@
 var _globalThis;
-if (typeof globalThis === 'object') {
-	_globalThis = globalThis;
-} else {
-	try {
-		_globalThis = require('es5-ext/global');
-	} catch (error) {
-	} finally {
-		if (!_globalThis && typeof window !== 'undefined') { _globalThis = window; }
-		if (!_globalThis) { throw new Error('Could not determine global this'); }
-	}
+
+/**
+ * core-js | Denis Pushkarev (zloirock) | MIT License
+ *
+ * https://github.com/zloirock/core-js/blob/977a3a49eb9473edf470cbc5c4257bd7c8c4da33/packages/core-js/internals/global-this.js#L1
+ */
+var checkGlobal = function (it) {
+  return it && it.Math === Math && it;
+};
+var _globalThis =
+	checkGlobal(typeof globalThis === 'object' && globalThis) ||
+	checkGlobal(typeof window === 'object' && window) ||
+	checkGlobal(typeof self === 'object' && self) ||
+	checkGlobal(typeof global === 'object' && global) ||
+	checkGlobal(typeof this === 'object' && this) ||
+	(function () { return this; })();
+
+if (!_globalThis) {
+	throw new Error('Could not determine global this');
 }
 
 var NativeWebSocket = _globalThis.WebSocket || _globalThis.MozWebSocket;
diff --git a/package.json b/package.json
index e59186fd..7365b7af 100644
--- a/package.json
+++ b/package.json
@@ -29,7 +29,6 @@
   "dependencies": {
     "bufferutil": "^4.0.1",
     "debug": "^2.2.0",
-    "es5-ext": "^0.10.63",
     "typedarray-to-buffer": "^3.1.5",
     "utf-8-validate": "^5.0.2",
     "yaeti": "^0.0.6"
@@ -38,8 +37,8 @@
     "buffer-equal": "^1.0.0",
     "gulp": "^4.0.2",
     "gulp-jshint": "^2.0.4",
-    "jshint-stylish": "^2.2.1",
     "jshint": "^2.0.0",
+    "jshint-stylish": "^2.2.1",
     "tape": "^4.9.1"
   },
   "config": {