diff --git a/include/boost/regex/config.hpp b/include/boost/regex/config.hpp
index a347bd34..3cea8998 100644
--- a/include/boost/regex/config.hpp
+++ b/include/boost/regex/config.hpp
@@ -42,6 +42,7 @@
 #  include BOOST_REGEX_USER_CONFIG
 
 #  include <boost/config.hpp>
+#  include <boost/predef.h>
 
 #else
    /*