diff --git a/src/sentry/integrations/slack/webhooks/event.py b/src/sentry/integrations/slack/webhooks/event.py
index 51450d9d8249f0..d43eaf046bc2d3 100644
--- a/src/sentry/integrations/slack/webhooks/event.py
+++ b/src/sentry/integrations/slack/webhooks/event.py
@@ -281,7 +281,7 @@ def on_link_shared(self, request: Request, slack_request: SlackDMRequest) -> boo
         if identity_user:
             sentry_sdk.set_user(
                 {
-                    "id": identity_user.id,
+                    "id": str(identity_user.id),
                     "email": identity_user.email,
                     "username": identity_user.username,
                 }