diff --git a/test_problems/cathermo/HMW_graph_GvT/HMW_graph_GvT.cpp b/test_problems/cathermo/HMW_graph_GvT/HMW_graph_GvT.cpp
index 2a7b646b6..4df5b191b 100644
--- a/test_problems/cathermo/HMW_graph_GvT/HMW_graph_GvT.cpp
+++ b/test_problems/cathermo/HMW_graph_GvT/HMW_graph_GvT.cpp
@@ -27,7 +27,7 @@
 
 #include "TemperatureTable.h"
 
-
+using namespace std;
 using namespace Cantera;
 
 class fileLog: public Logger {