diff --git a/concepts.cpp b/concepts.cpp
index d9d11253..36c46d77 100644
--- a/concepts.cpp
+++ b/concepts.cpp
@@ -26,8 +26,10 @@
 #include <iostream>
 
 #include <boost/numeric/ublas/vector.hpp>
+#include <boost/numeric/ublas/vector_proxy.hpp>
 #include <boost/numeric/ublas/vector_sparse.hpp>
 #include <boost/numeric/ublas/matrix.hpp>
+#include <boost/numeric/ublas/matrix_proxy.hpp>
 #include <boost/numeric/ublas/banded.hpp>
 #include <boost/numeric/ublas/triangular.hpp>
 #include <boost/numeric/ublas/symmetric.hpp>