diff --git a/src/popup/app/accounts/accountsLoginTwoFactorController.js b/src/popup/app/accounts/accountsLoginTwoFactorController.js
index c9684785ca..d3df2f32f4 100644
--- a/src/popup/app/accounts/accountsLoginTwoFactorController.js
+++ b/src/popup/app/accounts/accountsLoginTwoFactorController.js
@@ -19,7 +19,7 @@ angular
             customWebVaultUrl = environmentService.webVaultUrl;
         }
 
-        var u2f = new U2f(customWebVaultUrl, function (data) {
+        var u2f = new $window.U2f($window, customWebVaultUrl, function (data) {
             $timeout(function () {
                 $scope.login(data);
             });
diff --git a/src/popup/app/app.js b/src/popup/app/app.js
index 0c5c63e575..8aa66b9a22 100644
--- a/src/popup/app/app.js
+++ b/src/popup/app/app.js
@@ -14,11 +14,12 @@ require('angulartics-google-analytics');
 require('ng-infinite-scroll');
 
 require('../../scripts/duo.js');
-require('../../scripts/u2f.js');
 
 require('../less/libs.less');
 require('../less/popup.less');
 
+import U2f from '../../scripts/u2f';
+
 import Analytics from '../../scripts/analytics';
 new Analytics(window);
 
diff --git a/src/scripts/u2f.js b/src/scripts/u2f.js
deleted file mode 100644
index 7a36537090..0000000000
--- a/src/scripts/u2f.js
+++ /dev/null
@@ -1,87 +0,0 @@
-window.U2f = U2f = function U2f(webVaultUrl, successCallback, errorCallback, infoCallback) {
-    this.success = successCallback;
-    this.error = errorCallback;
-    this.info = infoCallback;
-    this.iframe = null;
-    this.connectorLink = document.createElement('a');
-    this.webVaultUrl = webVaultUrl && webVaultUrl !== '' ? webVaultUrl : 'https://vault.bitwarden.com';
-};
-
-(function () {
-    var thisU2f = null;
-
-    U2f.prototype.init = function (data) {
-        /* jshint ignore:start */
-        var self = thisU2f = this;
-        /* jshint ignore:end */
-
-        self.connectorLink.href = self.webVaultUrl + '/u2f-connector.html' +
-            '?data=' + this.base64Encode(JSON.stringify(data)) +
-            '&parent=' + encodeURIComponent(document.location.href) +
-            '&v=1';
-
-        self.iframe = document.getElementById('u2f_iframe');
-        self.iframe.src = self.connectorLink.href;
-
-        window.addEventListener('message', parseMessage, false);
-    };
-
-    U2f.prototype.validMessage = function (event) {
-        if (!event.origin || event.origin === '' || event.origin !== this.connectorLink.origin) {
-            return false;
-        }
-
-        return event.data.indexOf('success|') === 0 || event.data.indexOf('error|') === 0 || event.data.indexOf('info|') === 0;
-    };
-
-    U2f.prototype.stop = function () {
-        this.sendMessage('stop');
-    };
-
-    U2f.prototype.start = function () {
-        this.sendMessage('start');
-    };
-
-    U2f.prototype.sendMessage = function (message) {
-        var self = this;
-        if (!self.iframe || !self.iframe.src || !self.iframe.contentWindow) {
-            return;
-        }
-
-        self.iframe.contentWindow.postMessage(message, self.iframe.src);
-    };
-
-    U2f.prototype.base64Encode = function (str) {
-        return btoa(encodeURIComponent(str).replace(/%([0-9A-F]{2})/g, function (match, p1) {
-            return String.fromCharCode('0x' + p1);
-        }));
-    };
-
-    U2f.prototype.cleanup = function () {
-        window.removeEventListener('message', parseMessage, false);
-    };
-
-    function parseMessage(event) {
-        if (!thisU2f) {
-            return;
-        }
-
-        if (!thisU2f.validMessage(event)) {
-            thisU2f.error('Invalid message.');
-            return;
-        }
-
-        var parts = event.data.split('|');
-        if (parts[0] === 'success' && thisU2f.success) {
-            thisU2f.success(parts[1]);
-        }
-        else if (parts[0] === 'error' && thisU2f.error) {
-            thisU2f.error(parts[1]);
-        }
-        else if (parts[0] === 'info') {
-            if (thisU2f.info) {
-                thisU2f.info(parts[1]);
-            }
-        }
-    }
-})();
diff --git a/src/scripts/u2f.ts b/src/scripts/u2f.ts
new file mode 100644
index 0000000000..cbd482a029
--- /dev/null
+++ b/src/scripts/u2f.ts
@@ -0,0 +1,76 @@
+class U2f {
+    private iframe: HTMLIFrameElement = null;
+    private connectorLink: HTMLAnchorElement;
+
+    constructor(private win: Window, private webVaultUrl: string, private successCallback: Function,
+        private errorCallback: Function, private infoCallback: Function) {
+        this.connectorLink = win.document.createElement('a');
+        this.webVaultUrl = webVaultUrl != null && webVaultUrl !== '' ? webVaultUrl : 'https://vault.bitwarden.com';
+    }
+
+    init(data: any): void {
+        this.connectorLink.href = this.webVaultUrl + '/u2f-connector.html' +
+            '?data=' + this.base64Encode(JSON.stringify(data)) +
+            '&parent=' + encodeURIComponent(this.win.document.location.href) +
+            '&v=1';
+
+        this.iframe = this.win.document.getElementById('u2f_iframe') as HTMLIFrameElement;
+        this.iframe.src = this.connectorLink.href;
+
+        this.win.addEventListener('message', (e) => this.parseMessage(e), false);
+    }
+
+    stop() {
+        this.sendMessage('stop');
+    }
+
+    start() {
+        this.sendMessage('start');
+    }
+
+    sendMessage(message: any) {
+        if (!this.iframe || !this.iframe.src || !this.iframe.contentWindow) {
+            return;
+        }
+
+        this.iframe.contentWindow.postMessage(message, this.iframe.src);
+    }
+
+    base64Encode(str: string): string {
+        return btoa(encodeURIComponent(str).replace(/%([0-9A-F]{2})/g, (match, p1) => {
+            return String.fromCharCode(('0x' + p1) as any);
+        }));
+    }
+
+    cleanup() {
+        this.win.removeEventListener('message', (e) => this.parseMessage(e), false);
+    }
+
+    private parseMessage(event: any) {
+        if (!this.validMessage(event)) {
+            this.errorCallback('Invalid message.');
+            return;
+        }
+
+        const parts: string[] = event.data.split('|');
+        if (parts[0] === 'success' && this.successCallback) {
+            this.successCallback(parts[1]);
+        } else if (parts[0] === 'error' && this.errorCallback) {
+            this.errorCallback(parts[1]);
+        } else if (parts[0] === 'info' && this.infoCallback) {
+            this.infoCallback(parts[1]);
+        }
+    }
+
+    private validMessage(event: any) {
+        if (!event.origin || event.origin === '' || event.origin !== (this.connectorLink as any).origin) {
+            return false;
+        }
+
+        return event.data.indexOf('success|') === 0 || event.data.indexOf('error|') === 0 ||
+            event.data.indexOf('info|') === 0;
+    }
+}
+
+export { U2f };
+(window as any).U2f = U2f;