diff --git a/Cantera/src/thermo/VPSSMgrFactory.cpp b/Cantera/src/thermo/VPSSMgrFactory.cpp
index f8f1f17b2..5b78568a7 100644
--- a/Cantera/src/thermo/VPSSMgrFactory.cpp
+++ b/Cantera/src/thermo/VPSSMgrFactory.cpp
@@ -200,7 +200,7 @@ namespace Cantera {
   void VPSSMgrFactory::deleteFactory() {
 
 #if defined(THREAD_SAFE_CANTERA)
-      boost::mutex::scoped_lock lock(species_thermo_mutex);
+      boost::mutex::scoped_lock lock(vpss_species_thermo_mutex);
 #endif
       if (s_factory) {
 	delete s_factory;