diff --git a/examples/android-proguard-example/proguard.cfg b/examples/android-proguard-example/proguard.cfg
index 1a932cb96e..5c5e375c7f 100644
--- a/examples/android-proguard-example/proguard.cfg
+++ b/examples/android-proguard-example/proguard.cfg
@@ -13,9 +13,9 @@
 # Application classes that will be serialized/deserialized over Gson
 -keep class com.google.gson.examples.android.model.** { <fields>; }
 
-# Prevent proguard from stripping interface information from TypeAdapter, TypeAdapterFactory,
-# JsonSerializer, JsonDeserializer instances (so they can be used in @JsonAdapter)
--keep class * implements com.google.gson.TypeAdapter
+# Prevent proguard from stripping interface/abstract-class information from TypeAdapter,
+# TypeAdapterFactory, JsonSerializer, JsonDeserializer instances (so they can be used in @JsonAdapter)
+-keep class * extends com.google.gson.TypeAdapter
 -keep class * implements com.google.gson.TypeAdapterFactory
 -keep class * implements com.google.gson.JsonSerializer
 -keep class * implements com.google.gson.JsonDeserializer