diff --git a/lib/shared/unshim-utils.js b/lib/shared/unshim-utils.js
--- a/lib/shared/unshim-utils.js
+++ b/lib/shared/unshim-utils.js
@@ -43,6 +43,7 @@
   messageTypes.CREATE_SIDEBAR,
   messageTypes.SIDEBAR_SOURCE,
   messageTypes.MULTIMEDIA,
+  messageTypes.REACTION,
 ]);
 function unshimMessageInfos(
   messageInfos: $ReadOnlyArray<RawMessageInfo>,