diff --git a/dune/fufem/functions/sumfunction.hh b/dune/fufem/functions/sumfunction.hh
index c4024461f28c7aca19925a2f548a4a0574b8595f..983e1e5ecd574c3460c2df10b8208310fa7dcd74 100644
--- a/dune/fufem/functions/sumfunction.hh
+++ b/dune/fufem/functions/sumfunction.hh
@@ -33,7 +33,7 @@ public:
     /** \brief Constructor
      *
      */
-    SumFunction(std::vector<BaseType*>& functions, std::vector<double>& coefficients):
+    SumFunction(std::vector<const BaseType*>& functions, std::vector<double>& coefficients):
         functions_(functions),
         coefficients_(coefficients)
     {
@@ -70,7 +70,7 @@ public:
      * \param coefficient for summand function
      * \param function summand function to register
      */
-    virtual void registerFunction(double coefficient, BaseType& function)
+    virtual void registerFunction(double coefficient, const BaseType& function)
     {
         functions_.push_back(&function);
         coefficients_.push_back(coefficient);
@@ -79,7 +79,7 @@ public:
     ~SumFunction(){}
 
 private:
-    std::vector<BaseType*> functions_;
+    std::vector<const BaseType*> functions_;
     std::vector<double> coefficients_;
 
 };