diff --git a/lib/shared/dm-ops/change-thread-read-status-spec.js b/lib/shared/dm-ops/change-thread-read-status-spec.js
--- a/lib/shared/dm-ops/change-thread-read-status-spec.js
+++ b/lib/shared/dm-ops/change-thread-read-status-spec.js
@@ -1,5 +1,6 @@
 // @flow
 
+import invariant from 'invariant';
 import uuid from 'uuid';
 
 import type {
@@ -22,15 +23,39 @@
     },
     processDMOperation: async (
       dmOperation: DMChangeThreadReadStatusOperation,
+      viewerID: string,
+      utilities: ProcessDMOperationUtilities,
     ) => {
       const { threadID, unread, time } = dmOperation;
+
+      const threadInfo = utilities.threadInfos[threadID];
+      invariant(threadInfo.thick, 'Thread should be thick');
+      if (threadInfo.timestamps.currentUser.unread > time) {
+        return {
+          rawMessageInfos: [],
+          updateInfos: [],
+        };
+      }
+
       const updateInfos = [
         {
-          type: updateTypes.UPDATE_THREAD_READ_STATUS,
+          type: updateTypes.UPDATE_THREAD,
           id: uuid.v4(),
           time,
-          threadID,
-          unread,
+          threadInfo: {
+            ...threadInfo,
+            currentUser: {
+              ...threadInfo.currentUser,
+              unread,
+            },
+            timestamps: {
+              ...threadInfo.timestamps,
+              currentUser: {
+                ...threadInfo.timestamps.currentUser,
+                unread: time,
+              },
+            },
+          },
         },
       ];
       return {
diff --git a/lib/shared/dm-ops/process-dm-ops.js b/lib/shared/dm-ops/process-dm-ops.js
--- a/lib/shared/dm-ops/process-dm-ops.js
+++ b/lib/shared/dm-ops/process-dm-ops.js
@@ -31,7 +31,6 @@
 import type { RawThreadInfo } from '../../types/minimally-encoded-thread-permissions-types.js';
 import type { DispatchMetadata } from '../../types/redux-types.js';
 import type { OutboundP2PMessage } from '../../types/sqlite-types.js';
-import { threadTypes } from '../../types/thread-types-enum.js';
 import type { LegacyRawThreadInfo } from '../../types/thread-types.js';
 import { updateTypes } from '../../types/update-types-enum.js';
 import { extractUserIDsFromPayload } from '../../utils/conversion-utils.js';
@@ -194,10 +193,7 @@
         const updatedThreadInfo = updateSpecs[
           update.type
         ].getUpdatedThreadInfo?.(update, updatedThreadInfosByThreadID);
-        if (
-          updatedThreadInfo &&
-          updatedThreadInfo?.type === threadTypes.THICK_SIDEBAR
-        ) {
+        if (updatedThreadInfo) {
           updatedThreadInfosByThreadID[updatedThreadInfo.id] =
             updatedThreadInfo;
         }