diff --git a/test/cpp/qps/qps_driver.cc b/test/cpp/qps/qps_driver.cc
index eceb5103f6a..d5348463650 100644
--- a/test/cpp/qps/qps_driver.cc
+++ b/test/cpp/qps/qps_driver.cc
@@ -132,6 +132,9 @@ static void QpsDriver() {
       pareto->set_alpha(FLAGS_load_param_2);
       break;
     }
+    default:
+      GPR_ASSERT(false);
+      break;
   }
 
   ServerConfig server_config;