diff --git a/package.json b/package.json
index c316af7..31ecaa2 100644
--- a/package.json
+++ b/package.json
@@ -29,7 +29,6 @@
   },
   "homepage": "https://github.com/Brightspace/node-ecdsa-sig-formatter#readme",
   "dependencies": {
-    "base64url": "^2.0.0",
     "safe-buffer": "^5.0.1"
   },
   "devDependencies": {
diff --git a/src/ecdsa-sig-formatter.js b/src/ecdsa-sig-formatter.js
index 07430e1..38eeb9b 100644
--- a/src/ecdsa-sig-formatter.js
+++ b/src/ecdsa-sig-formatter.js
@@ -1,6 +1,5 @@
 'use strict';
 
-var base64Url = require('base64url').fromBase64;
 var Buffer = require('safe-buffer').Buffer;
 
 var getParamBytesForAlg = require('./param-bytes-for-alg');
@@ -13,6 +12,13 @@ var MAX_OCTET = 0x80,
 	ENCODED_TAG_SEQ = (TAG_SEQ | PRIMITIVE_BIT) | (CLASS_UNIVERSAL << 6),
 	ENCODED_TAG_INT = TAG_INT | (CLASS_UNIVERSAL << 6);
 
+function base64Url(base64) {
+	return base64
+		.replace(/=/g, '')
+		.replace(/\+/g, '-')
+		.replace(/\//g, '_');
+}
+
 function signatureAsBuffer(signature) {
 	if (Buffer.isBuffer(signature)) {
 		return signature;