diff --git a/mautrix_telegram/portal.py b/mautrix_telegram/portal.py
index 40ecc63d..6f0f51f6 100644
--- a/mautrix_telegram/portal.py
+++ b/mautrix_telegram/portal.py
@@ -3688,7 +3688,7 @@ async def handle_telegram_action(
                 end_reason = "disconnected"
             body = f"{call_type} {end_reason}"
             if action.duration:
-                body += f" ({format_duration(action.duration)}"
+                body += f" ({format_duration(action.duration)})"
             await self._send_message(
                 sender.intent_for(self),
                 TextMessageEventContent(msgtype=MessageType.NOTICE, body=body),