diff --git a/include/chaiscript/dispatchkit/proxy_functions.hpp b/include/chaiscript/dispatchkit/proxy_functions.hpp
index 0d83b83..dae5162 100644
--- a/include/chaiscript/dispatchkit/proxy_functions.hpp
+++ b/include/chaiscript/dispatchkit/proxy_functions.hpp
@@ -13,6 +13,7 @@
 #include "type_info.hpp"
 #include <string>
 #include <boost/function.hpp>
+#include <boost/type_traits/add_reference.hpp>
 #include <stdexcept>
 #include <vector>
 #include "proxy_functions_detail.hpp"
diff --git a/include/chaiscript/language/chaiscript_engine.hpp b/include/chaiscript/language/chaiscript_engine.hpp
index 2a1f9c0..7adb0e5 100644
--- a/include/chaiscript/language/chaiscript_engine.hpp
+++ b/include/chaiscript/language/chaiscript_engine.hpp
@@ -348,8 +348,10 @@ namespace chaiscript
          */
         State get_state()
         {
+#ifndef CHAISCRIPT_NO_THREADS
             boost::lock_guard<boost::recursive_mutex> l(use_mutex);
             boost::shared_lock<boost::shared_mutex> l2(mutex);
+#endif
 
             State s;
             s.loaded_files = loaded_files;
@@ -363,8 +365,10 @@ namespace chaiscript
          */
         void set_state(const State &t_state)
         {
+#ifndef CHAISCRIPT_NO_THREADS
             boost::lock_guard<boost::recursive_mutex> l(use_mutex);
             boost::shared_lock<boost::shared_mutex> l2(mutex);
+#endif
 
             loaded_files = t_state.loaded_files;
             active_loaded_modules = t_state.active_loaded_modules;