diff --git a/include/boost/numeric/ublas/lu.hpp b/include/boost/numeric/ublas/lu.hpp
index 25027c7d..73b5fed2 100644
--- a/include/boost/numeric/ublas/lu.hpp
+++ b/include/boost/numeric/ublas/lu.hpp
@@ -21,6 +21,7 @@
 #include <boost/numeric/ublas/vector_proxy.hpp>
 #include <boost/numeric/ublas/matrix_proxy.hpp>
 #include <boost/numeric/ublas/vector.hpp>
+#include <boost/numeric/ublas/triangular.hpp>
 
 // LU factorizations in the spirit of LAPACK and Golub & van Loan