diff --git a/src/codegen/extensions/slack/types.py b/src/codegen/extensions/slack/types.py
index 8be37efc6..04d96e433 100644
--- a/src/codegen/extensions/slack/types.py
+++ b/src/codegen/extensions/slack/types.py
@@ -30,6 +30,7 @@ class SlackEvent(BaseModel):
     blocks: list[Block] | None = None
     channel: str
     event_ts: str
+    thread_ts: str | None = None
 
 
 class SlackWebhookPayload(BaseModel):