diff --git a/test_problems/mixGasTransport/mixGasTransport.cpp b/test_problems/mixGasTransport/mixGasTransport.cpp
index 67fca2ab0..f742a0f17 100644
--- a/test_problems/mixGasTransport/mixGasTransport.cpp
+++ b/test_problems/mixGasTransport/mixGasTransport.cpp
@@ -39,6 +39,7 @@ using namespace std;
 #include "kernel/TransportFactory.h"
 
 using namespace Cantera;
+using namespace Cantera_CXX;
 
 void printDbl(double val) {
   if (fabs(val) < 5.0E-17) {