diff --git a/include/boost/type_traits/is_complex.hpp b/include/boost/type_traits/is_complex.hpp
index 7cf04b4..c4554ce 100644
--- a/include/boost/type_traits/is_complex.hpp
+++ b/include/boost/type_traits/is_complex.hpp
@@ -8,6 +8,7 @@
 #ifndef BOOST_TT_IS_COMPLEX_HPP
 #define BOOST_TT_IS_COMPLEX_HPP
 
+#include <boost/config.hpp>
 #include <complex>
 #include <boost/type_traits/integral_constant.hpp>