diff --git a/InCallUI/proguard.flags b/InCallUI/proguard.flags
index 8fa10e0..bc88143 100644
--- a/InCallUI/proguard.flags
+++ b/InCallUI/proguard.flags
@@ -1,3 +1,8 @@
 -keep class com.android.incallui.widget.multiwaveview.* {
   *;
 }
+
+# Keep names that are used only by animation framework.
+-keepclasseswithmembers class com.android.incallui.AnimationUtils$CrossFadeDrawable {
+    *** setCrossFadeAlpha(...);
+}