diff --git a/AMDiS/src/GenericOperatorTerm.h b/AMDiS/src/GenericOperatorTerm.h
index de504250e75fab48639a9831130c7318797a049d..92d16d5ad868154cdf7cfdff8ae56f4fd83ae173 100644
--- a/AMDiS/src/GenericOperatorTerm.h
+++ b/AMDiS/src/GenericOperatorTerm.h
@@ -785,7 +785,7 @@ eval(AbstractFunction<TOut, WorldVector<double> >* fct) { return function_(wrap(
 
 template<typename Term>
 inline typename boost::enable_if<typename boost::is_base_of<LazyOperatorTermBase, Term>::type, typename Term::value_type>::type
-integrate(Term term);
+integrate(Term term, Mesh* mesh_ = NULL);
 
 
 template<typename Term>
diff --git a/AMDiS/src/GenericOperatorTerm.hh b/AMDiS/src/GenericOperatorTerm.hh
index 2bb86b179ef84cc257df66a8bdfac97851df9a8d..d05ee149f5acfa0cac505fc3d936883c33c4b14d 100644
--- a/AMDiS/src/GenericOperatorTerm.hh
+++ b/AMDiS/src/GenericOperatorTerm.hh
@@ -53,7 +53,7 @@ namespace AMDiS {
 
 template<typename Term>
 inline typename boost::enable_if<typename boost::is_base_of<LazyOperatorTermBase, Term>::type, typename Term::value_type>::type
-integrate(Term term, Mesh* mesh_ = NULL)
+integrate(Term term, Mesh* mesh_)
 {
   typedef typename Term::value_type TOut;