diff --git a/opm/core/transport/CSRMatrixBlockAssembler.hpp b/opm/core/transport/CSRMatrixBlockAssembler.hpp
index 342ce45..4e5b4fc 100644
--- a/opm/core/transport/CSRMatrixBlockAssembler.hpp
+++ b/opm/core/transport/CSRMatrixBlockAssembler.hpp
@@ -36,6 +36,7 @@
 #ifndef OPM_CSRMATRIXBLOCKASSEMBLER_HPP_HEADER
 #define OPM_CSRMATRIXBLOCKASSEMBLER_HPP_HEADER
 
+#include <cassert>
 #include <cstddef>
 #include <cstdlib>