diff --git a/include/boost/python/object_core.hpp b/include/boost/python/object_core.hpp
index d41b18ad..a9b51ac6 100755
--- a/include/boost/python/object_core.hpp
+++ b/include/boost/python/object_core.hpp
@@ -218,7 +218,7 @@ namespace api
       PyObject* m_ptr;
   };
 
-# if BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
+# ifdef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
   template <class T, class U>
   struct is_derived_impl
   {