diff --git a/src/learning_gem5/part2/hello_object.hh b/src/learning_gem5/part2/hello_object.hh
index c34dde304d..05c6dde4d6 100644
--- a/src/learning_gem5/part2/hello_object.hh
+++ b/src/learning_gem5/part2/hello_object.hh
@@ -69,7 +69,7 @@ class HelloObject : public SimObject
      * SimObjects have been constructed. It is called after the user calls
      * simulate() for the first time.
      */
-    void startup();
+    void startup() override;
 };
 
 } // namespace gem5