diff --git a/lib/shared/messages/reaction-message-spec.js b/lib/shared/messages/reaction-message-spec.js
--- a/lib/shared/messages/reaction-message-spec.js
+++ b/lib/shared/messages/reaction-message-spec.js
@@ -19,6 +19,15 @@
   RawReactionMessageInfo,
   ReactionMessageInfo,
 > = Object.freeze({
+  messageContentForServerDB(
+    data: ReactionMessageData | RawReactionMessageInfo,
+  ): string {
+    return JSON.stringify({
+      reaction: data.reaction,
+      action: data.action,
+    });
+  },
+
   messageContentForClientDB(data: RawReactionMessageInfo): string {
     return JSON.stringify({
       targetMessageID: data.targetMessageID,