diff --git a/opm/parser/eclipse/EclipseState/EclipseState.hpp b/opm/parser/eclipse/EclipseState/EclipseState.hpp
index fac310174..2c1a6a408 100644
--- a/opm/parser/eclipse/EclipseState/EclipseState.hpp
+++ b/opm/parser/eclipse/EclipseState/EclipseState.hpp
@@ -133,7 +133,7 @@ namespace Opm {
         NNC m_nnc;
 
         MessageContainer m_messageContainer;
-        const UnitSystem& m_deckUnitSystem;
+        UnitSystem m_deckUnitSystem;
     };
 
     typedef std::shared_ptr<EclipseState> EclipseStatePtr;