diff --git a/include/regex b/include/regex
index efd91eec..1156a3e5 100644
--- a/include/regex
+++ b/include/regex
@@ -1008,6 +1008,10 @@ private:
     int __value(wchar_t __ch, int __radix) const;
 };
 
+template <class _CharT>
+const typename regex_traits<_CharT>::char_class_type
+regex_traits<_CharT>::__regex_word;
+
 template <class _CharT>
 regex_traits<_CharT>::regex_traits()
 {