diff --git a/lib/main.dart b/lib/main.dart
index 6e47bb4..46baa65 100644
--- a/lib/main.dart
+++ b/lib/main.dart
@@ -164,7 +164,8 @@ class _KioskMainPageState extends State<KioskMainPage> {
             try {
               // base64 decode into string
               var decodedQrContent = base64.decode(qrContent);
-              var clientConfig = jsonDecode(decodedQrContent.toString());
+              var clientConfig = jsonDecode(decodedQrContent.toString())
+                  .cast<Map<String, dynamic>>();
               if (clientConfig.containsKey('config_endpoint') &&
                   clientConfig.containsKey('token')) {
                 setState(() {