diff --git a/core/proguard.flags b/core/proguard.flags
index 5148e56..367c56d 100644
--- a/core/proguard.flags
+++ b/core/proguard.flags
@@ -41,12 +41,12 @@
 # Needed to ensure callback field references are kept in their respective
 # owning classes when the downstream callback registrars only store weak refs.
 -if @com.android.internal.annotations.WeaklyReferencedCallback class *
--keepclassmembers,allowaccessmodification class * {
-  <1> *;
+-keepclassmembers,allowaccessmodification,allowobfuscation,allowshrinking class * {
+  !synthetic <1> *;
 }
 -if class * extends @com.android.internal.annotations.WeaklyReferencedCallback **
--keepclassmembers,allowaccessmodification class * {
-  <1> *;
+-keepclassmembers,allowaccessmodification,allowobfuscation,allowshrinking class * {
+  !synthetic <1> *;
 }
 
 # Understand the common @Keep annotation from various Android packages: