diff --git a/specific/wave/equation/simplewave.h b/specific/wave/equation/simplewave.h
index 2cbe35d648b5d907c4ebe90f62096b9ffa384909..5582cbab8453d47b9586b3b3505d5c9db90fc0a2 100644
--- a/specific/wave/equation/simplewave.h
+++ b/specific/wave/equation/simplewave.h
@@ -22,6 +22,7 @@ namespace simplewave
         double _const_preconditioner;
         using EquationInterface<Physic::acoustic>::_boundary;
         std::string _topBC;
+        bool _useSecondOrderABC;
     public:
         Equation(unsigned int f_idx,double pulsation,const ConfigurationInterface* const config, const wave::Discretization<Physic::acoustic>& w_discret,const gmshfem::common::GmshFem& gmshFem, std::string suffix = "");