diff --git a/google/protobuf/test_messages_proto2.proto b/google/protobuf/test_messages_proto2.proto
index b04d8bb475e33..73bd626c43b1e 100644
--- a/google/protobuf/test_messages_proto2.proto
+++ b/google/protobuf/test_messages_proto2.proto
@@ -40,6 +40,7 @@ syntax = "proto2";
 package protobuf_test_messages.proto2;
 
 option java_package = "com.google.protobuf_test_messages.proto2";
+option objc_class_prefix = "Proto2";
 
 // This is the default, but we specify it here explicitly.
 option optimize_for = SPEED;