diff --git a/include/boost/math/distributions/landau.hpp b/include/boost/math/distributions/landau.hpp
index 90cd0aaa8..e84c95e4a 100644
--- a/include/boost/math/distributions/landau.hpp
+++ b/include/boost/math/distributions/landau.hpp
@@ -13,6 +13,7 @@
 
 #include <boost/math/distributions/fwd.hpp>
 #include <boost/math/constants/constants.hpp>
+#include <boost/math/tools/big_constant.hpp>
 #include <boost/math/distributions/complement.hpp>
 #include <boost/math/distributions/detail/common_error_handling.hpp>
 #include <boost/math/distributions/detail/derived_accessors.hpp>