diff --git a/tracetools_test/src/test_ping.cpp b/tracetools_test/src/test_ping.cpp
index 5a1cafa..b419e72 100644
--- a/tracetools_test/src/test_ping.cpp
+++ b/tracetools_test/src/test_ping.cpp
@@ -69,7 +69,12 @@ private:
 
 int main(int argc, char * argv[])
 {
-  bool do_only_one = argc == 1;
+  bool do_only_one = true;
+  for (int i = 0; i < argc; ++i) {
+    if (strncmp(argv[i], "do_more", 7) == 0) {
+      do_only_one = false;
+    }
+  }
 
   rclcpp::init(argc, argv);
 
diff --git a/tracetools_test/src/test_pong.cpp b/tracetools_test/src/test_pong.cpp
index f1d52b8..9e8167c 100644
--- a/tracetools_test/src/test_pong.cpp
+++ b/tracetools_test/src/test_pong.cpp
@@ -58,7 +58,12 @@ private:
 
 int main(int argc, char * argv[])
 {
-  bool do_only_one = argc == 1;
+  bool do_only_one = true;
+  for (int i = 0; i < argc; ++i) {
+    if (strncmp(argv[i], "do_more", 7) == 0) {
+      do_only_one = false;
+    }
+  }
 
   rclcpp::init(argc, argv);