diff --git a/isso/js/app/lib/itsdangerous.js b/isso/js/app/lib/itsdangerous.js
index 0a4a4fd..8d29c92 100644
--- a/isso/js/app/lib/itsdangerous.js
+++ b/isso/js/app/lib/itsdangerous.js
@@ -5,7 +5,7 @@ define(function() {
     var epoch = 1293840000;
 
     var decode = function(str) {
-        return atob(str + new Array(str.length % 4 + 1).join("="));
+        return atob(str + new Array(4 - str.length % 4 + 1).join("="));
     };
 
     var timestamp = function(str) {
diff --git a/isso/utils/__init__.py b/isso/utils/__init__.py
index 5ca3967..e2cc48a 100644
--- a/isso/utils/__init__.py
+++ b/isso/utils/__init__.py
@@ -114,7 +114,7 @@ class URLSafeTimedSerializer(TimedSerializer):
 
     def load_payload(self, payload):
         try:
-            json = base64.b64decode(payload + b"=" * (len(payload) % 4))
+            json = base64.b64decode(payload + b"=" * (-len(payload) % 4))
         except Exception as e:
             raise BadPayload('Could not base64 decode the payload because of '
                              'an exception', original_error=e)