diff --git a/Cantera/cxx/include/thermo.h b/Cantera/cxx/include/thermo.h
index 41291fcee..c66b09c7b 100755
--- a/Cantera/cxx/include/thermo.h
+++ b/Cantera/cxx/include/thermo.h
@@ -10,5 +10,6 @@
 #define CT_THERMO_INCL
 
 #include "kernel/thermo/SingleSpeciesTP.h"
+#include "kernel/thermo/StoichSubstanceSSTP.h"
 
 #endif