diff --git a/include/boost/system/detail/generic_category.hpp b/include/boost/system/detail/generic_category.hpp
index d9ee1b5..cc125f6 100644
--- a/include/boost/system/detail/generic_category.hpp
+++ b/include/boost/system/detail/generic_category.hpp
@@ -11,7 +11,7 @@
 //  See library home page at http://www.boost.org/libs/system
 
 #include <boost/system/detail/error_category.hpp>
-#include <boost/system/detail/generic_category_impl.hpp>
+#include <boost/system/detail/generic_category_message.hpp>
 #include <boost/system/detail/config.hpp>
 #include <boost/cstdint.hpp>
 #include <boost/config.hpp>
diff --git a/include/boost/system/detail/generic_category_impl.hpp b/include/boost/system/detail/generic_category_message.hpp
similarity index 89%
rename from include/boost/system/detail/generic_category_impl.hpp
rename to include/boost/system/detail/generic_category_message.hpp
index 5b968ad..fbdb41a 100644
--- a/include/boost/system/detail/generic_category_impl.hpp
+++ b/include/boost/system/detail/generic_category_message.hpp
@@ -1,7 +1,7 @@
-#ifndef BOOST_SYSTEM_DETAIL_GENERIC_CATEGORY_IMPL_HPP_INCLUDED
-#define BOOST_SYSTEM_DETAIL_GENERIC_CATEGORY_IMPL_HPP_INCLUDED
+#ifndef BOOST_SYSTEM_DETAIL_GENERIC_CATEGORY_MESSAGE_HPP_INCLUDED
+#define BOOST_SYSTEM_DETAIL_GENERIC_CATEGORY_MESSAGE_HPP_INCLUDED
 
-// Implementation details of generic_error_category
+// Implementation of generic_error_category_message
 //
 // Copyright 2018 Peter Dimov
 //
@@ -105,4 +105,4 @@ inline char const * generic_error_category_message( int ev, char * buffer, std::
 
 } // namespace boost
 
-#endif // #ifndef BOOST_SYSTEM_DETAIL_GENERIC_CATEGORY_IMPL_HPP_INCLUDED
+#endif // #ifndef BOOST_SYSTEM_DETAIL_GENERIC_CATEGORY_MESSAGE_HPP_INCLUDED