diff --git a/build_tests/proto.cc b/build_tests/proto.cc
index 23ff879..bb09003 100644
--- a/build_tests/proto.cc
+++ b/build_tests/proto.cc
@@ -6,6 +6,7 @@
   ::frc971::TestProto test_proto1, test_proto2;
   test_proto1.set_s("Hi!");
   test_proto1.set_i(971);
+  test_proto1.mutable_base_proto()->set_a("silly");
 
   ::std::string serialized;
   ASSERT_TRUE(test_proto1.SerializeToString(&serialized));