diff --git a/test/functions_test.cppipe b/test/functions_test.cppipe
index 88ffe93..30bfa71 100755
--- a/test/functions_test.cppipe
+++ b/test/functions_test.cppipe
@@ -75,8 +75,6 @@ int main(int argc, char* argv[])
 
 	run({ "echo", "OK 12/13" });
 
-	exec({ "echo", "OK 13/13" });
-
-	// todo
-	// exec( echo + $(echo + "OK 11/13") );
+	// The temporaty string is desroyed after the statement
+	exec( echo + $(echo + "OK 13/13").c_str() );
 }