diff --git a/quickstep/src/com/android/quickstep/views/FloatingWidgetBackgroundView.java b/quickstep/src/com/android/quickstep/views/FloatingWidgetBackgroundView.java
index c3b166f..adea1a4 100644
--- a/quickstep/src/com/android/quickstep/views/FloatingWidgetBackgroundView.java
+++ b/quickstep/src/com/android/quickstep/views/FloatingWidgetBackgroundView.java
@@ -136,7 +136,7 @@
     }
 
     /** Returns the maximum corner radius of {@param drawable}. */
-    private static float getMaxRadius(Drawable drawable) {
+    private static float getMaxRadius(@Nullable Drawable drawable) {
         if (!(drawable instanceof GradientDrawable)) return 0;
         float[] cornerRadii = ((GradientDrawable) drawable).getCornerRadii();
         float cornerRadius = ((GradientDrawable) drawable).getCornerRadius();