diff --git a/base64-js/base64-js-tests.ts b/base64-js/base64-js-tests.ts
index 6852ddb626..13c3f705b5 100644
--- a/base64-js/base64-js-tests.ts
+++ b/base64-js/base64-js-tests.ts
@@ -1,6 +1,5 @@
-/// <reference path="base64-js.d.ts" />
+import * as base64js from "base64-js";
 
-import * as base64js from 'base64-js';
-
-const bytes: Uint8Array = base64js.toByteArray('shemp');
+const length: number = base64js.byteLength("");
+const bytes: Uint8Array = base64js.toByteArray("");
 const decoded: string = base64js.fromByteArray(new Uint8Array(0));
diff --git a/base64-js/index.d.ts b/base64-js/index.d.ts
index a029f384c3..7a38667368 100644
--- a/base64-js/index.d.ts
+++ b/base64-js/index.d.ts
@@ -1,7 +1,8 @@
-// Type definitions for base64-js v1.1.2
+// Type definitions for base64-js 1.2
 // Project: https://github.com/beatgammit/base64-js
 // Definitions by: Peter Safranek <https://github.com/pe8ter>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 
+export function byteLength(encoded: string): number;
 export function toByteArray(encoded: string): Uint8Array;
-export function fromByteArray(bytes: Uint8Array): string;
\ No newline at end of file
+export function fromByteArray(bytes: Uint8Array): string;
diff --git a/base64-js/tsconfig.json b/base64-js/tsconfig.json
index dc8ef6a70a..0d0c14d324 100644
--- a/base64-js/tsconfig.json
+++ b/base64-js/tsconfig.json
@@ -3,7 +3,7 @@
         "module": "commonjs",
         "target": "es6",
         "noImplicitAny": true,
-        "strictNullChecks": false,
+        "strictNullChecks": true,
         "baseUrl": "../",
         "typeRoots": [
             "../"
@@ -14,6 +14,6 @@
     },
     "files": [
         "index.d.ts",
-        "base64-js-test.ts"
+        "base64-js-tests.ts"
     ]
 }
\ No newline at end of file