diff --git a/keyserver/src/responders/message-responders.js b/keyserver/src/responders/message-responders.js
--- a/keyserver/src/responders/message-responders.js
+++ b/keyserver/src/responders/message-responders.js
@@ -192,7 +192,6 @@
 
 const sendReactionMessageRequestInputValidator = tShape({
   threadID: t.String,
-  localID: t.String,
   targetMessageID: t.String,
   reaction: tString('👍'),
   action: t.enums.of(['add_reaction', 'remove_reaction']),
@@ -204,7 +203,7 @@
   const request: SendReactionMessageRequest = input;
   await validateInput(viewer, sendReactionMessageRequestInputValidator, input);
 
-  const { threadID, localID, targetMessageID, reaction, action } = request;
+  const { threadID, targetMessageID, reaction, action } = request;
 
   if (!targetMessageID || !reaction) {
     throw new ServerError('invalid_parameters');
@@ -248,7 +247,6 @@
   const messageData: ReactionMessageData = {
     type: messageTypes.REACTION,
     threadID,
-    localID,
     creatorID: viewer.id,
     time: Date.now(),
     targetMessageID,
diff --git a/lib/actions/message-actions.js b/lib/actions/message-actions.js
--- a/lib/actions/message-actions.js
+++ b/lib/actions/message-actions.js
@@ -216,7 +216,6 @@
     'create_reaction_message',
     {
       threadID: request.threadID,
-      localID: request.localID,
       targetMessageID: request.targetMessageID,
       reaction: request.reaction,
       action: request.action,