diff --git a/lib/reducers/message-reducer.js b/lib/reducers/message-reducer.js
--- a/lib/reducers/message-reducer.js
+++ b/lib/reducers/message-reducer.js
@@ -1127,24 +1127,38 @@
     const newMessageIDs = messageStore.threads[threadID].messageIDs.filter(
       id => id !== localID,
     );
+    const newThread = {
+      ...messageStore.threads[threadID],
+      messageIDs: newMessageIDs,
+    };
+
+    messageStoreOperations.push({
+      type: 'replace_thread',
+      payload: { threads: { [threadID]: newThread } },
+    });
 
     const processedMessageStore = processMessageStoreOperations(
       messageStore,
       messageStoreOperations,
     );
 
+    const newMessageStore = {
+      ...processedMessageStore,
+      threads: {
+        ...messageStore.threads,
+        [threadID]: newThread,
+      },
+    };
+
+    assertMessageStoreThreadsAreEqual(
+      processedMessageStore,
+      newMessageStore,
+      `${action.type} | reaction failure`,
+    );
+
     return {
       messageStoreOperations,
-      messageStore: {
-        ...processedMessageStore,
-        threads: {
-          ...messageStore.threads,
-          [threadID]: {
-            ...messageStore.threads[threadID],
-            messageIDs: newMessageIDs,
-          },
-        },
-      },
+      messageStore: newMessageStore,
     };
   } else if (
     action.type === sendTextMessageActionTypes.success ||