diff --git a/android-app/proguard.cfg b/android-app/proguard.cfg
index 4931cac7..eb27a90b 100644
--- a/android-app/proguard.cfg
+++ b/android-app/proguard.cfg
@@ -70,9 +70,12 @@
 -keep class * implements org.solovyev.android.calculator.model.MathPersistenceEntity
 -keep class * implements org.solovyev.android.calculator.MathEntityPersistenceContainer
 
+# Allow obfuscation of android.support.v7.internal.view.menu.**
+# to avoid problem on Samsung 4.2.2 devices with appcompat v21
+# see https://code.google.com/p/android/issues/detail?id=78377
 -keep class android.support.v4.app.** { *; }
 -keep interface android.support.v4.app.** { *; }
--keep class android.support.v7.** { *; }
+-keep class !android.support.v7.internal.view.menu.MenuBuilder, !android.support.v7.internal.view.menu.SubMenuBuilder, android.support.v7.** { *; }
 -keep interface android.support.v7.** { *; }
 
 #