diff --git a/services/core/java/com/android/server/display/BrightnessTracker.java b/services/core/java/com/android/server/display/BrightnessTracker.java
index 88df195e8051c41498f53c4e69f47c1dd793b4e0..905c7e371294e613f54e04bd1106c0a33cdaa5ef 100644
--- a/services/core/java/com/android/server/display/BrightnessTracker.java
+++ b/services/core/java/com/android/server/display/BrightnessTracker.java
@@ -686,10 +686,15 @@ public class BrightnessTracker {
     }
 
     public ParceledListSlice<AmbientBrightnessDayStats> getAmbientBrightnessStats(int userId) {
-        ArrayList<AmbientBrightnessDayStats> stats = mAmbientBrightnessStatsTracker.getUserStats(
-                userId);
-        return (stats != null) ? new ParceledListSlice<>(stats) : new ParceledListSlice<>(
-                Collections.EMPTY_LIST);
+        if (mAmbientBrightnessStatsTracker != null) {
+            ArrayList<AmbientBrightnessDayStats> stats =
+                    mAmbientBrightnessStatsTracker.getUserStats(
+                            userId);
+            if (stats != null) {
+                return new ParceledListSlice<>(stats);
+            }
+        }
+        return ParceledListSlice.emptyList();
     }
 
     // Not allowed to keep the SensorEvent so used to copy the data we care about.
diff --git a/services/tests/servicestests/src/com/android/server/display/BrightnessTrackerTest.java b/services/tests/servicestests/src/com/android/server/display/BrightnessTrackerTest.java
index 92cc537ada6dd176ffee3e258cfb7806a19e7a3c..45bee6e89ddb72624f770f56022f94c27d3f231b 100644
--- a/services/tests/servicestests/src/com/android/server/display/BrightnessTrackerTest.java
+++ b/services/tests/servicestests/src/com/android/server/display/BrightnessTrackerTest.java
@@ -30,9 +30,11 @@ import android.content.ContentResolver;
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
+import android.content.pm.ParceledListSlice;
 import android.database.ContentObserver;
 import android.hardware.SensorEvent;
 import android.hardware.SensorEventListener;
+import android.hardware.display.AmbientBrightnessDayStats;
 import android.hardware.display.BrightnessChangeEvent;
 import android.os.BatteryManager;
 import android.os.Handler;
@@ -571,6 +573,19 @@ public class BrightnessTrackerTest {
         assertEquals(event.batteryLevel, event2.batteryLevel, FLOAT_DELTA);
     }
 
+    @Test
+    public void testNonNullAmbientStats() {
+        // getAmbientBrightnessStats should return an empty list rather than null when
+        // tracker isn't started or hasn't collected any data.
+        ParceledListSlice<AmbientBrightnessDayStats> slice = mTracker.getAmbientBrightnessStats(0);
+        assertNotNull(slice);
+        assertTrue(slice.getList().isEmpty());
+        startTracker(mTracker);
+        slice = mTracker.getAmbientBrightnessStats(0);
+        assertNotNull(slice);
+        assertTrue(slice.getList().isEmpty());
+    }
+
     private InputStream getInputStream(String data) {
         return new ByteArrayInputStream(data.getBytes(StandardCharsets.UTF_8));
     }