--- a/taskcluster/taskgraph/actions/registry.py
+++ b/taskcluster/taskgraph/actions/registry.py
@@ -188,17 +188,17 @@ def register_callback_action(name, title
             task_group_id = os.environ.get('TASK_ID', slugid())
 
             return {
                 'created': {'$fromNow': ''},
                 'deadline': {'$fromNow': '12 hours'},
                 'expires': {'$fromNow': '1 year'},
                 'metadata': {
                     'owner': 'mozilla-taskcluster-maintenance@mozilla.com',
-                    'source': '{}raw-file/{}/{}'.format(
+                    'source': '{}/raw-file/{}/{}'.format(
                         parameters['head_repository'], parameters['head_rev'], source_path,
                     ),
                     'name': 'Action: {}'.format(title),
                     'description': 'Task executing callback for action.\n\n---\n' + description,
                 },
                 'workerType': 'gecko-{}-decision'.format(parameters['level']),
                 'provisionerId': 'aws-provisioner-v1',
                 'taskGroupId': task_group_id,