diff --git a/app/src/main/java/com/topjohnwu/magisk/ClassMap.java b/app/src/main/java/com/topjohnwu/magisk/ClassMap.java
deleted file mode 100644
index 4013d5918..000000000
--- a/app/src/main/java/com/topjohnwu/magisk/ClassMap.java
+++ /dev/null
@@ -1,31 +0,0 @@
-package com.topjohnwu.magisk;
-
-import com.topjohnwu.magisk.model.download.DownloadModuleService;
-import com.topjohnwu.magisk.model.receiver.GeneralReceiver;
-import com.topjohnwu.magisk.model.update.UpdateCheckService;
-import com.topjohnwu.magisk.ui.MainActivity;
-import com.topjohnwu.magisk.ui.SplashActivity;
-import com.topjohnwu.magisk.ui.flash.FlashActivity;
-import com.topjohnwu.magisk.ui.surequest.SuRequestActivity;
-
-import java.util.HashMap;
-import java.util.Map;
-
-public class ClassMap {
-    private static Map<Class, Class> classMap = new HashMap<>();
-
-    static {
-        classMap.put(App.class, a.e.class);
-        classMap.put(MainActivity.class, a.b.class);
-        classMap.put(SplashActivity.class, a.c.class);
-        classMap.put(FlashActivity.class, a.f.class);
-        classMap.put(UpdateCheckService.class, a.g.class);
-        classMap.put(GeneralReceiver.class, a.h.class);
-        classMap.put(DownloadModuleService.class, a.j.class);
-        classMap.put(SuRequestActivity.class, a.m.class);
-    }
-    
-    public static <T> Class<T> get(Class c) {
-        return classMap.get(c);
-    }
-}
diff --git a/app/src/main/java/com/topjohnwu/magisk/ClassMap.kt b/app/src/main/java/com/topjohnwu/magisk/ClassMap.kt
new file mode 100644
index 000000000..92ce3a884
--- /dev/null
+++ b/app/src/main/java/com/topjohnwu/magisk/ClassMap.kt
@@ -0,0 +1,27 @@
+package com.topjohnwu.magisk
+
+import com.topjohnwu.magisk.model.download.DownloadModuleService
+import com.topjohnwu.magisk.model.receiver.GeneralReceiver
+import com.topjohnwu.magisk.model.update.UpdateCheckService
+import com.topjohnwu.magisk.ui.MainActivity
+import com.topjohnwu.magisk.ui.SplashActivity
+import com.topjohnwu.magisk.ui.flash.FlashActivity
+import com.topjohnwu.magisk.ui.surequest.SuRequestActivity
+
+object ClassMap {
+    private val map = mapOf(
+        App::class.java to a.e::class.java,
+        MainActivity::class.java to a.b::class.java,
+        SplashActivity::class.java to a.c::class.java,
+        FlashActivity::class.java to a.f::class.java,
+        UpdateCheckService::class.java to a.g::class.java,
+        GeneralReceiver::class.java to a.h::class.java,
+        DownloadModuleService::class.java to a.j::class.java,
+        SuRequestActivity::class.java to a.m::class.java
+    )
+
+    @JvmStatic
+    operator fun get(c: Class<*>): Class<*>? {
+        return map.getOrElse(c) { null } //as? Class<T>
+    }
+}
diff --git a/app/src/main/java/com/topjohnwu/magisk/model/receiver/GeneralReceiver.kt b/app/src/main/java/com/topjohnwu/magisk/model/receiver/GeneralReceiver.kt
index 725736b50..e5b030905 100644
--- a/app/src/main/java/com/topjohnwu/magisk/model/receiver/GeneralReceiver.kt
+++ b/app/src/main/java/com/topjohnwu/magisk/model/receiver/GeneralReceiver.kt
@@ -41,7 +41,7 @@ open class GeneralReceiver : BroadcastReceiver() {
                 }
                 when (action) {
                     SuRequestActivity.REQUEST -> {
-                        val i = Intent(context, ClassMap.get<Any>(SuRequestActivity::class.java))
+                        val i = Intent(context, ClassMap[SuRequestActivity::class.java])
                             .setAction(action)
                             .putExtra("socket", intent.getStringExtra("socket"))
                             .addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
diff --git a/app/src/main/java/com/topjohnwu/magisk/ui/MainActivity.kt b/app/src/main/java/com/topjohnwu/magisk/ui/MainActivity.kt
index 57c86b028..1aa718252 100644
--- a/app/src/main/java/com/topjohnwu/magisk/ui/MainActivity.kt
+++ b/app/src/main/java/com/topjohnwu/magisk/ui/MainActivity.kt
@@ -48,7 +48,7 @@ open class MainActivity : MagiskActivity<MainViewModel, ActivityMainBinding>() {
 
     override fun onCreate(savedInstanceState: Bundle?) {
         if (!SplashActivity.DONE) {
-            startActivity(Intent(this, ClassMap.get<Any>(SplashActivity::class.java)))
+            startActivity(Intent(this, ClassMap[SplashActivity::class.java]))
             finish()
         }
 
diff --git a/app/src/main/java/com/topjohnwu/magisk/ui/SplashActivity.kt b/app/src/main/java/com/topjohnwu/magisk/ui/SplashActivity.kt
index 24df89c3d..f75fb2483 100644
--- a/app/src/main/java/com/topjohnwu/magisk/ui/SplashActivity.kt
+++ b/app/src/main/java/com/topjohnwu/magisk/ui/SplashActivity.kt
@@ -66,7 +66,7 @@ open class SplashActivity : AppCompatActivity() {
             //UpdateRepos().exec()
         }
 
-        val intent = Intent(this, ClassMap.get<Any>(MainActivity::class.java))
+        val intent = Intent(this, ClassMap[MainActivity::class.java])
         intent.putExtra(Const.Key.OPEN_SECTION, getIntent().getStringExtra(Const.Key.OPEN_SECTION))
         DONE = true
         startActivity(intent)
diff --git a/app/src/main/java/com/topjohnwu/magisk/ui/module/ModulesFragment.kt b/app/src/main/java/com/topjohnwu/magisk/ui/module/ModulesFragment.kt
index 9aff75076..08a14441f 100644
--- a/app/src/main/java/com/topjohnwu/magisk/ui/module/ModulesFragment.kt
+++ b/app/src/main/java/com/topjohnwu/magisk/ui/module/ModulesFragment.kt
@@ -28,7 +28,7 @@ class ModulesFragment : MagiskFragment<ModuleViewModel, FragmentModulesBinding>(
     override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
         if (requestCode == Const.ID.FETCH_ZIP && resultCode == Activity.RESULT_OK && data != null) {
             // Get the URI of the selected file
-            val intent = Intent(activity, ClassMap.get<Any>(FlashActivity::class.java))
+            val intent = Intent(activity, ClassMap[FlashActivity::class.java])
             intent.setData(data.data).putExtra(Const.Key.FLASH_ACTION, Const.Value.FLASH_ZIP)
             startActivity(intent)
         }
diff --git a/app/src/main/java/com/topjohnwu/magisk/ui/module/ReposFragment.kt b/app/src/main/java/com/topjohnwu/magisk/ui/module/ReposFragment.kt
index 4cc750e68..2ed02d623 100644
--- a/app/src/main/java/com/topjohnwu/magisk/ui/module/ReposFragment.kt
+++ b/app/src/main/java/com/topjohnwu/magisk/ui/module/ReposFragment.kt
@@ -82,7 +82,7 @@ class ReposFragment : MagiskFragment<ModuleViewModel, FragmentReposBinding>(),
 
         fun download(install: Boolean) {
             context.runWithExternalRW {
-                val intent = Intent(activity, ClassMap.get<Any>(DownloadModuleService::class.java))
+                val intent = Intent(activity, ClassMap[DownloadModuleService::class.java])
                     .putExtra("repo", item).putExtra("install", install)
                 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                     context.startForegroundService(intent) //hmm, service starts itself in foreground, this seems unnecessary
diff --git a/app/src/main/java/com/topjohnwu/magisk/utils/Utils.java b/app/src/main/java/com/topjohnwu/magisk/utils/Utils.java
index af954af5f..cc7d9f068 100644
--- a/app/src/main/java/com/topjohnwu/magisk/utils/Utils.java
+++ b/app/src/main/java/com/topjohnwu/magisk/utils/Utils.java
@@ -30,6 +30,7 @@ import java.util.concurrent.TimeUnit;
 import androidx.annotation.WorkerThread;
 import androidx.work.Constraints;
 import androidx.work.ExistingPeriodicWorkPolicy;
+import androidx.work.ListenableWorker;
 import androidx.work.NetworkType;
 import androidx.work.PeriodicWorkRequest;
 import androidx.work.WorkManager;
@@ -110,13 +111,15 @@ public class Utils {
         return BuildConfig.VERSION_NAME.contains("-");
     }
 
+    @SuppressWarnings("unchecked")
     public static void scheduleUpdateCheck() {
         if (Config.get(Config.Key.CHECK_UPDATES)) {
             Constraints constraints = new Constraints.Builder()
                     .setRequiredNetworkType(NetworkType.CONNECTED)
                     .build();
+            Class<? extends ListenableWorker> service = (Class<? extends ListenableWorker>) ClassMap.get(UpdateCheckService.class);
             PeriodicWorkRequest request = new PeriodicWorkRequest
-                    .Builder(ClassMap.get(UpdateCheckService.class), 12, TimeUnit.HOURS)
+                    .Builder(service, 12, TimeUnit.HOURS)
                     .setConstraints(constraints)
                     .build();
             WorkManager.getInstance().enqueueUniquePeriodicWork(