diff --git a/core/java/android/view/IWindowFocusObserver.aidl b/core/java/android/view/IWindowFocusObserver.aidl
index d14bb4817a67e..3b23c777b188e 100644
--- a/core/java/android/view/IWindowFocusObserver.aidl
+++ b/core/java/android/view/IWindowFocusObserver.aidl
@@ -16,7 +16,7 @@
 package android.view;
 
 /** {@hide} */
-interface IWindowFocusObserver
+oneway interface IWindowFocusObserver
 {
     void focusGained(IBinder inputToken);
     void focusLost(IBinder inputToken);