diff --git a/packages/SystemUI/src/com/android/systemui/util/sensors/ProximitySensor.java b/packages/SystemUI/src/com/android/systemui/util/sensors/ProximitySensor.java
index c5a66a7c7fe2f..19c477dfe0a53 100644
--- a/packages/SystemUI/src/com/android/systemui/util/sensors/ProximitySensor.java
+++ b/packages/SystemUI/src/com/android/systemui/util/sensors/ProximitySensor.java
@@ -86,9 +86,12 @@ public class ProximitySensor implements ThresholdSensor {
         public void onThresholdCrossed(ThresholdSensorEvent event) {
             // If we no longer have a "below" signal and the secondary sensor is not
             // considered "safe", then we need to turn it off.
-            if (!mSecondarySafe && (!mLastPrimaryEvent.getBelow() || !event.getBelow())) {
+            if (!mSecondarySafe
+                    && (mLastPrimaryEvent == null
+                    || !mLastPrimaryEvent.getBelow()
+                    || !event.getBelow())) {
                 mSecondaryThresholdSensor.pause();
-                if (!mLastPrimaryEvent.getBelow()) {
+                if (mLastPrimaryEvent == null || !mLastPrimaryEvent.getBelow()) {
                     // Only check the secondary as long as the primary thinks we're near.
                     mCancelSecondaryRunnable = null;
                     return;
@@ -100,7 +103,9 @@ public class ProximitySensor implements ThresholdSensor {
             }
             logDebug("Secondary sensor event: " + event.getBelow() + ".");
 
-            onSensorEvent(event);
+            if (!mPaused) {
+                onSensorEvent(event);
+            }
         }
     };
 
@@ -252,9 +257,10 @@ public class ProximitySensor implements ThresholdSensor {
             return;
         }
         if (mLastEvent != null) {
+            ThresholdSensorEvent lastEvent = mLastEvent;  // Listeners can null out mLastEvent.
             List<ThresholdSensor.Listener> listeners = new ArrayList<>(mListeners);
             listeners.forEach(proximitySensorListener ->
-                    proximitySensorListener.onThresholdCrossed(mLastEvent));
+                    proximitySensorListener.onThresholdCrossed(lastEvent));
         }
 
         mAlerting.set(false);
diff --git a/packages/SystemUI/tests/src/com/android/systemui/util/sensors/ProximitySensorDualTest.java b/packages/SystemUI/tests/src/com/android/systemui/util/sensors/ProximitySensorDualTest.java
index bb498d7bdefdc..bae1d98aa3102 100644
--- a/packages/SystemUI/tests/src/com/android/systemui/util/sensors/ProximitySensorDualTest.java
+++ b/packages/SystemUI/tests/src/com/android/systemui/util/sensors/ProximitySensorDualTest.java
@@ -152,6 +152,32 @@ public class ProximitySensorDualTest extends SysuiTestCase {
         assertFalse(mProximitySensor.isRegistered());
     }
 
+    @Test
+    public void testUnregisterDuringCallback() {
+        ThresholdSensor.Listener listenerA = event -> mProximitySensor.pause();
+        TestableListener listenerB = new TestableListener();
+
+        assertFalse(mProximitySensor.isRegistered());
+        mProximitySensor.register(listenerA);
+        mProximitySensor.register(listenerB);
+        assertTrue(mProximitySensor.isRegistered());
+        assertFalse(mThresholdSensorPrimary.isPaused());
+        assertTrue(mThresholdSensorSecondary.isPaused());
+        assertNull(listenerB.mLastEvent);
+
+        // listenerA will pause the proximity sensor, unregistering it.
+        mThresholdSensorPrimary.triggerEvent(true, 0);
+        mThresholdSensorSecondary.triggerEvent(true, 0);
+        assertTrue(listenerB.mLastEvent.getBelow());
+        assertEquals(1, listenerB.mCallCount);
+
+
+        // A second call to trigger it should be ignored.
+        mThresholdSensorSecondary.triggerEvent(false, 0);
+        assertTrue(listenerB.mLastEvent.getBelow());
+        assertEquals(1, listenerB.mCallCount);
+    }
+
     @Test
     public void testPauseAndResume() {
         TestableListener listener = new TestableListener();