diff --git a/roles/notifs/backend/templates/fmn.consumer.py b/roles/notifs/backend/templates/fmn.consumer.py
index 59c041bc61..7858e46617 100644
--- a/roles/notifs/backend/templates/fmn.consumer.py
+++ b/roles/notifs/backend/templates/fmn.consumer.py
@@ -32,6 +32,9 @@ class MutexLock(AbstractFileLock):
     def release_write_lock(self):
         return self.mutex.release_write_lock()
 
+    def __json__(self):
+        return repr(self)
+
 
 config = {
     {% if env == 'staging' %}