diff --git a/quickstep/src/com/android/quickstep/HighResLoadingState.kt b/quickstep/src/com/android/quickstep/HighResLoadingState.kt
index 8a21c4f613..aabaecfdfe 100644
--- a/quickstep/src/com/android/quickstep/HighResLoadingState.kt
+++ b/quickstep/src/com/android/quickstep/HighResLoadingState.kt
@@ -18,6 +18,7 @@ package com.android.quickstep
 
 import android.content.res.Resources
 import com.android.quickstep.recents.data.HighResLoadingStateNotifier
+import java.util.concurrent.CopyOnWriteArrayList
 
 /** Determines when high res or low res thumbnails should be loaded. */
 class HighResLoadingState : HighResLoadingStateNotifier {
@@ -38,7 +39,7 @@ class HighResLoadingState : HighResLoadingStateNotifier {
     var isEnabled: Boolean = false
         private set
 
-    private val callbacks = ArrayList<HighResLoadingStateChangedCallback>()
+    private val callbacks = CopyOnWriteArrayList<HighResLoadingStateChangedCallback>()
 
     interface HighResLoadingStateChangedCallback {
         fun onHighResLoadingStateChanged(enabled: Boolean)
@@ -56,7 +57,7 @@ class HighResLoadingState : HighResLoadingStateNotifier {
         val prevState = isEnabled
         isEnabled = forceHighResThumbnails || (visible && !flingingFast)
         if (prevState != isEnabled) {
-            for (callback in callbacks.asReversed()) {
+            for (callback in callbacks) {
                 callback.onHighResLoadingStateChanged(isEnabled)
             }
         }