diff --git a/ui/src/sso.js b/ui/src/sso.js
index 7208154536b504bf54b4f067aeece6810eaeefa1..3c445595a5be81a8f26ff75423a12532eef936e0 100644
--- a/ui/src/sso.js
+++ b/ui/src/sso.js
@@ -13,7 +13,7 @@ function bufferEncode(value) {
 }
 
 function bufferDecode(value) {
-    return Uint8Array.from(atob(value), c => c.charCodeAt(0));
+    return Uint8Array.from(atob(value.replace(/-/g, '+').replace(/_/g, '/')), c => c.charCodeAt(0));
 }
 
 function verifyAssertion(url, assertedCredential) {