diff --git a/extensions/qa-lab/src/live-transports/slack/slack-live.observations.ts b/extensions/qa-lab/src/live-transports/slack/slack-live.observations.ts
index 19bb7e642dd7..67533edd6c18 100644
--- a/extensions/qa-lab/src/live-transports/slack/slack-live.observations.ts
+++ b/extensions/qa-lab/src/live-transports/slack/slack-live.observations.ts
@@ -71,7 +71,7 @@ export async function listSlackMessages(params: {
   client: WebClient;
   oldestTs: string;
 }) {
-  const messages: SlackMessage[] = [];
+  const messages: NonNullable<ReturnType<typeof slackHistorySchema.parse>["messages"]> = [];
   let cursor: string | undefined;
   for (let page = 0; page < SLACK_QA_CHANNEL_HISTORY_MAX_PAGES; page += 1) {
     const history = slackHistorySchema.parse(