diff --git a/packages/SystemUI/src/com/android/systemui/broadcast/UserBroadcastDispatcher.kt b/packages/SystemUI/src/com/android/systemui/broadcast/UserBroadcastDispatcher.kt
index 24357a740331e..d50666c1b3cf0 100644
--- a/packages/SystemUI/src/com/android/systemui/broadcast/UserBroadcastDispatcher.kt
+++ b/packages/SystemUI/src/com/android/systemui/broadcast/UserBroadcastDispatcher.kt
@@ -27,6 +27,8 @@ import android.os.UserHandle
 import android.util.ArrayMap
 import android.util.ArraySet
 import android.util.Log
+import androidx.annotation.MainThread
+import com.android.internal.util.Preconditions
 import com.android.systemui.Dumpable
 import java.io.FileDescriptor
 import java.io.PrintWriter
@@ -72,7 +74,14 @@ class UserBroadcastDispatcher(
 
     internal fun isRegistered() = registered.get()
 
-    private val registerReceiver = Runnable {
+    // Only modify in BG thread
+    private val actionsToReceivers = ArrayMap<String, MutableSet<ReceiverData>>()
+    private val receiverToReceiverData = ArrayMap<BroadcastReceiver, MutableSet<ReceiverData>>()
+
+    // Only call on BG thread as it reads from the maps
+    private fun createFilter(): IntentFilter {
+        Preconditions.checkState(bgHandler.looper.isCurrentThread,
+                "This method should only be called from BG thread")
         val categories = mutableSetOf<String>()
         receiverToReceiverData.values.flatten().forEach {
             it.filter.categoriesIterator()?.asSequence()?.let {
@@ -80,30 +89,13 @@ class UserBroadcastDispatcher(
             }
         }
         val intentFilter = IntentFilter().apply {
-            actionsToReceivers.keys.forEach { addAction(it) }
+            // The keys of the arrayMap are of type String! so null check is needed
+            actionsToReceivers.keys.forEach { if (it != null) addAction(it) else Unit }
             categories.forEach { addCategory(it) }
         }
-
-        if (registered.get()) {
-            context.unregisterReceiver(this)
-            registered.set(false)
-        }
-        // Short interval without receiver, this can be problematic
-        if (intentFilter.countActions() > 0 && !registered.get()) {
-            context.registerReceiverAsUser(
-                    this,
-                    UserHandle.of(userId),
-                    intentFilter,
-                    null,
-                    bgHandler)
-            registered.set(true)
-        }
+        return intentFilter
     }
 
-    // Only modify in BG thread
-    private val actionsToReceivers = ArrayMap<String, MutableSet<ReceiverData>>()
-    private val receiverToReceiverData = ArrayMap<BroadcastReceiver, MutableSet<ReceiverData>>()
-
     override fun onReceive(context: Context, intent: Intent) {
         val id = if (DEBUG) index.getAndIncrement() else 0
         if (DEBUG) Log.w(TAG, "[$id] Received $intent")
@@ -126,6 +118,8 @@ class UserBroadcastDispatcher(
     }
 
     private fun handleRegisterReceiver(receiverData: ReceiverData) {
+        Preconditions.checkState(bgHandler.looper.isCurrentThread,
+                "This method should only be called from BG thread")
         if (DEBUG) Log.w(TAG, "Register receiver: ${receiverData.receiver}")
         receiverToReceiverData.getOrPut(receiverData.receiver, { ArraySet() }).add(receiverData)
         var changed = false
@@ -138,11 +132,13 @@ class UserBroadcastDispatcher(
             }.add(receiverData)
         }
         if (changed) {
-            mainHandler.post(registerReceiver)
+            createFilterAndRegisterReceiverBG()
         }
     }
 
     private fun handleUnregisterReceiver(receiver: BroadcastReceiver) {
+        Preconditions.checkState(bgHandler.looper.isCurrentThread,
+                "This method should only be called from BG thread")
         if (DEBUG) Log.w(TAG, "Unregister receiver: $receiver")
         val actions = receiverToReceiverData.getOrElse(receiver) { return }
                 .flatMap { it.filter.actionsIterator().asSequence().asIterable() }.toSet()
@@ -156,10 +152,16 @@ class UserBroadcastDispatcher(
             }
         }
         if (changed) {
-            mainHandler.post(registerReceiver)
+            createFilterAndRegisterReceiverBG()
         }
     }
 
+    // Only call this from a BG thread
+    private fun createFilterAndRegisterReceiverBG() {
+        val intentFilter = createFilter()
+        mainHandler.post(RegisterReceiverRunnable(intentFilter))
+    }
+
     override fun dump(fd: FileDescriptor, pw: PrintWriter, args: Array<out String>) {
         pw.println("  Registered=${registered.get()}")
         actionsToReceivers.forEach { (action, list) ->
@@ -191,4 +193,30 @@ class UserBroadcastDispatcher(
                     }
         }
     }
+
+    private inner class RegisterReceiverRunnable(val intentFilter: IntentFilter) : Runnable {
+
+        /*
+         * Registers and unregisters the BroadcastReceiver
+         *
+         * Must be called from Main Thread
+         */
+        @MainThread
+        override fun run() {
+            if (registered.get()) {
+                context.unregisterReceiver(this@UserBroadcastDispatcher)
+                registered.set(false)
+            }
+            // Short interval without receiver, this can be problematic
+            if (intentFilter.countActions() > 0 && !registered.get()) {
+                context.registerReceiverAsUser(
+                        this@UserBroadcastDispatcher,
+                        UserHandle.of(userId),
+                        intentFilter,
+                        null,
+                        bgHandler)
+                registered.set(true)
+            }
+        }
+    }
 }