diff --git a/libraries/transformer/src/test/java/androidx/media3/transformer/TransformerTestRunner.java b/libraries/transformer/src/test/java/androidx/media3/transformer/TransformerTestRunner.java
index a739428697..03f4c020ea 100644
--- a/libraries/transformer/src/test/java/androidx/media3/transformer/TransformerTestRunner.java
+++ b/libraries/transformer/src/test/java/androidx/media3/transformer/TransformerTestRunner.java
@@ -22,6 +22,9 @@ import androidx.annotation.Nullable;
 import androidx.media3.common.MediaItem;
 import androidx.media3.test.utils.robolectric.RobolectricUtil;
 import java.util.concurrent.TimeoutException;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicReference;
+import org.checkerframework.checker.nullness.compatqual.NullableType;
 
 /** Helper class to run a {@link Transformer} test. */
 public final class TransformerTestRunner {
@@ -68,28 +71,27 @@ public final class TransformerTestRunner {
   @Nullable
   private static TransformationException runUntilListenerCalled(Transformer transformer)
       throws TimeoutException {
-    TransformationResult transformationResult = new TransformationResult();
+    AtomicBoolean transformationCompleted = new AtomicBoolean();
+    AtomicReference<@NullableType TransformationException> transformationException =
+        new AtomicReference<>();
+
     transformer.addListener(
         new Transformer.Listener() {
           @Override
           public void onTransformationCompleted(MediaItem inputMediaItem) {
-            transformationResult.isCompleted = true;
+            transformationCompleted.set(true);
           }
 
           @Override
           public void onTransformationError(
               MediaItem inputMediaItem, TransformationException exception) {
-            transformationResult.exception = exception;
+            transformationException.set(exception);
           }
         });
     runLooperUntil(
         transformer.getApplicationLooper(),
-        () -> transformationResult.isCompleted || transformationResult.exception != null);
-    return transformationResult.exception;
-  }
+        () -> transformationCompleted.get() || transformationException.get() != null);
 
-  private static class TransformationResult {
-    public boolean isCompleted;
-    @Nullable public TransformationException exception;
+    return transformationException.get();
   }
 }