diff --git a/lib/utils/message-ops-utils.js b/lib/utils/message-ops-utils.js
--- a/lib/utils/message-ops-utils.js
+++ b/lib/utils/message-ops-utils.js
@@ -35,7 +35,7 @@
 ): $ReadOnlyArray<ClientDBMediaInfo> {
   const clientDBMediaInfos = [];
   for (const m of media) {
-    const type =
+    const type: 'photo' | 'video' =
       m.type === 'encrypted_photo'
         ? 'photo'
         : m.type === 'encrypted_video'