diff --git a/mautrix_amp/user.py b/mautrix_amp/user.py
index d16971e9c75dfd2874c0e42eb09c1fb27940cd58..e90c4f58c3c5d7c26ba2df41712e4872e16070e5 100644
--- a/mautrix_amp/user.py
+++ b/mautrix_amp/user.py
@@ -54,6 +54,7 @@ class User(DBUser, BaseUser):
         self.log = self.log.getChild(self.mxid)
         self._metric_value = defaultdict(lambda: False)
         self._connection_check_task = None
+        self.dm_update_lock = asyncio.Lock()
         self.client = None
         self.intent = None