diff --git a/src/matrix/room/timeline/persistence/GapWriter.js b/src/matrix/room/timeline/persistence/GapWriter.js
index 92908df6..40ae5420 100644
--- a/src/matrix/room/timeline/persistence/GapWriter.js
+++ b/src/matrix/room/timeline/persistence/GapWriter.js
@@ -242,6 +242,7 @@ export class GapWriter {
             previousToken: null,
             nextToken: null
         };
+        txn.timelineFragments.add(newFragment);
         const eventKey = EventKey.defaultFragmentKey(newFragment.id);
 
         const startEntry = FragmentBoundaryEntry.start(newFragment, this._fragmentIdComparer);