diff --git a/app/build.gradle b/app/build.gradle
index 10da5cae..7d0e9e99 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -24,8 +24,8 @@ android {
         targetSdkVersion target_sdk_version
         minSdkVersion min_sdk_version
 
-        versionCode 490
-        versionName "4.9.0"
+        versionCode 491
+        versionName "4.9.1"
         applicationId "jp.juggler.subwaytooter"
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
         vectorDrawables.useSupportLibrary = true
diff --git a/app/src/main/java/jp/juggler/subwaytooter/notification/PollingUtils.kt b/app/src/main/java/jp/juggler/subwaytooter/notification/PollingUtils.kt
index 15dd08ab..dbfd5cc9 100644
--- a/app/src/main/java/jp/juggler/subwaytooter/notification/PollingUtils.kt
+++ b/app/src/main/java/jp/juggler/subwaytooter/notification/PollingUtils.kt
@@ -3,7 +3,10 @@ package jp.juggler.subwaytooter.notification
 import android.app.NotificationManager
 import android.content.Context
 import android.net.Uri
-import androidx.work.*
+import androidx.work.WorkInfo
+import androidx.work.WorkManager
+import androidx.work.WorkQuery
+import androidx.work.await
 import com.google.firebase.messaging.FirebaseMessaging
 import jp.juggler.subwaytooter.App1
 import jp.juggler.subwaytooter.api.TootApiClient
@@ -138,7 +141,7 @@ suspend fun cancelAllWorkAndJoin(context: Context) {
     val workManager = WorkManager.getInstance(context)
     repeat(3) {
         while (true) {
-            workManager.pruneWork()
+            workManager.pruneWork().await()
             val workQuery = WorkQuery.Builder.fromStates(
                 listOf(
                     WorkInfo.State.ENQUEUED,
@@ -152,7 +155,7 @@ suspend fun cancelAllWorkAndJoin(context: Context) {
             val list = workManager.getWorkInfos(workQuery).await()
             if (list.isEmpty()) break
             list.forEach {
-                workManager.cancelWorkById(it.id)
+                workManager.cancelWorkById(it.id).await()
             }
             delay(333L)
         }