diff --git a/test_problems/ChemEquil_red1/basopt_red1.cpp b/test_problems/ChemEquil_red1/basopt_red1.cpp
index 3a31ba098..7c9bea129 100644
--- a/test_problems/ChemEquil_red1/basopt_red1.cpp
+++ b/test_problems/ChemEquil_red1/basopt_red1.cpp
@@ -11,6 +11,7 @@
 
 using namespace std;
 using namespace Cantera;
+using namespace Cantera_CXX;
 
 int main(int argc, char **argv) {
   try {