diff --git a/src/action/updateappactivities.ts b/src/action/updateappactivities.ts
index 39813ba..496ba0b 100644
--- a/src/action/updateappactivities.ts
+++ b/src/action/updateappactivities.ts
@@ -16,7 +16,7 @@
  */
 
 import { AppActivityItem, RemovedAppActivityItem, SerializedAppActivityItem, SerializedRemovedAppActivityItem } from '../model/appactivity'
-import { assertNonEmptyListWithoutDuplicates } from '../util/list'
+import { assertListWithoutDuplicates } from '../util/list'
 import { AppLogicAction } from './basetypes'
 
 export class UpdateAppActivitiesAction extends AppLogicAction {
@@ -29,8 +29,8 @@ export class UpdateAppActivitiesAction extends AppLogicAction {
   }) {
     super()
 
-    assertNonEmptyListWithoutDuplicates(removed.map((item) => item.packageName + ':' + item.activityName))
-    assertNonEmptyListWithoutDuplicates(updatedOrAdded.map((item) => item.packageName + ':' + item.activityName))
+    assertListWithoutDuplicates(removed.map((item) => item.packageName + ':' + item.activityName))
+    assertListWithoutDuplicates(updatedOrAdded.map((item) => item.packageName + ':' + item.activityName))
 
     if (removed.length === 0 && updatedOrAdded.length === 0) {
       throw new Error('UpdateAppActivitiesAction is empty')
diff --git a/src/api/sync.ts b/src/api/sync.ts
index 414113b..4781e82 100644
--- a/src/api/sync.ts
+++ b/src/api/sync.ts
@@ -39,7 +39,9 @@ export const createSyncRouter = ({ database, websocket, connectedDevicesManager
 }) => {
   const router = Router()
 
-  router.post('/push-actions', json(), async (req, res, next) => {
+  router.post('/push-actions', json({
+    limit: '500kb'
+  }), async (req, res, next) => {
     try {
       if (!isClientPushChangesRequest(req.body)) {
         throw new BadRequest()
diff --git a/src/util/list.ts b/src/util/list.ts
index f2b3785..5c1c969 100644
--- a/src/util/list.ts
+++ b/src/util/list.ts
@@ -26,3 +26,9 @@ export function assertNonEmptyListWithoutDuplicates (list: Array<string>) {
     throw new Error('expected list without duplicates')
   }
 }
+
+export function assertListWithoutDuplicates (list: Array<string>) {
+  if (uniq(list).length !== list.length) {
+    throw new Error('expected list without duplicates')
+  }
+}