diff --git a/.gitignore b/.gitignore
index 509cbb6..5dc4499 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 *.so
 __pycache__
+build/
diff --git a/src/storage/model.cpp b/src/storage/model.cpp
index 02f32a5..370ceb5 100644
--- a/src/storage/model.cpp
+++ b/src/storage/model.cpp
@@ -33,8 +33,8 @@ void define_model(py::module& m) {
     ;
 
     // ModelBase
-    py::class_<storm::models::ModelBase, std::shared_ptr<storm::models::ModelBase>>(m, "ModelBase", "Base class for all models")
-        .def_property_readonly("nr_states", &storm::models::ModelBase::getNumberOfStates, "Number of states")
+    py::class_<storm::models::ModelBase, std::shared_ptr<storm::models::ModelBase>> modelBase(m, "ModelBase", "Base class for all models");
+    modelBase.def_property_readonly("nr_states", &storm::models::ModelBase::getNumberOfStates, "Number of states")
         .def_property_readonly("nr_transitions", &storm::models::ModelBase::getNumberOfTransitions, "Number of transitions")
         .def_property_readonly("model_type", &storm::models::ModelBase::getType, "Model type")
         .def_property_readonly("supports_parameters", &storm::models::ModelBase::supportsParameters, "Flag whether model supports parameters")
@@ -47,21 +47,23 @@ void define_model(py::module& m) {
     ;
 
     // Models
-    py::class_<storm::models::sparse::Model<double>, std::shared_ptr<storm::models::sparse::Model<double>>>(m, "SparseModel", "A probabilistic model where transitions are represented by doubles and saved in a sparse matrix", py::base<storm::models::ModelBase>())
-        .def_property_readonly("labels", [](storm::models::sparse::Model<double>& model) {
-                return model.getStateLabeling().getLabels();
-            }, "Labels")
+//storm::models::sparse::Model<double, storm::models::sparse::StandardRewardModel<double> >
+
+    py::class_<storm::models::sparse::Model<double>, std::shared_ptr<storm::models::sparse::Model<double>>> model(m, "SparseModel", "A probabilistic model where transitions are represented by doubles and saved in a sparse matrix", modelBase);
+    model.def_property_readonly("labels", [](storm::models::sparse::Model<double>& model) {
+            return model.getStateLabeling().getLabels();
+        }, "Labels")
         .def("labels_state", &storm::models::sparse::Model<double>::getLabelsOfState, py::arg("state"), "Get labels of state")
         .def_property_readonly("initial_states", &getInitialStates<double>, "Initial states")
         .def_property_readonly("transition_matrix", &getTransitionMatrix<double>, py::return_value_policy::reference, py::keep_alive<1, 0>(), "Transition matrix")
-    ;    
-    py::class_<storm::models::sparse::Dtmc<double>, std::shared_ptr<storm::models::sparse::Dtmc<double>>>(m, "SparseDtmc", "DTMC in sparse representation", py::base<storm::models::sparse::Model<double>>())
     ;
-    py::class_<storm::models::sparse::Mdp<double>, std::shared_ptr<storm::models::sparse::Mdp<double>>>(m, "SparseMdp", "MDP in sparse representation", py::base<storm::models::sparse::Model<double>>())
+    py::class_<storm::models::sparse::Dtmc<double>, std::shared_ptr<storm::models::sparse::Dtmc<double>>>(m, "SparseDtmc", "DTMC in sparse representation", model)
+    ;
+    py::class_<storm::models::sparse::Mdp<double>, std::shared_ptr<storm::models::sparse::Mdp<double>>>(m, "SparseMdp", "MDP in sparse representation", model)
     ;
 
-    py::class_<storm::models::sparse::Model<storm::RationalFunction>, std::shared_ptr<storm::models::sparse::Model<storm::RationalFunction>>>(m, "SparseParametricModel", "A probabilistic model where transitions are represented by rational functions and saved in a sparse matrix", py::base<storm::models::ModelBase>())
-        .def("collect_probability_parameters", &storm::models::sparse::getProbabilityParameters, "Collect parameters")
+    py::class_<storm::models::sparse::Model<storm::RationalFunction>, std::shared_ptr<storm::models::sparse::Model<storm::RationalFunction>>> modelRatFunc(m, "SparseParametricModel", "A probabilistic model where transitions are represented by rational functions and saved in a sparse matrix", modelBase);
+    modelRatFunc.def("collect_probability_parameters", &storm::models::sparse::getProbabilityParameters, "Collect parameters")
         .def_property_readonly("labels", [](storm::models::sparse::Model<storm::RationalFunction>& model) {
                 return model.getStateLabeling().getLabels();
             }, "Labels")
@@ -69,9 +71,9 @@ void define_model(py::module& m) {
         .def_property_readonly("initial_states", &getInitialStates<storm::RationalFunction>, "Initial states")
         .def_property_readonly("transition_matrix", &getTransitionMatrix<storm::RationalFunction>, py::return_value_policy::reference, py::keep_alive<1, 0>(), "Transition matrix")
     ;
-    py::class_<storm::models::sparse::Dtmc<storm::RationalFunction>, std::shared_ptr<storm::models::sparse::Dtmc<storm::RationalFunction>>>(m, "SparseParametricDtmc", "pDTMC in sparse representation", py::base<storm::models::sparse::Model<storm::RationalFunction>>())
+    py::class_<storm::models::sparse::Dtmc<storm::RationalFunction>, std::shared_ptr<storm::models::sparse::Dtmc<storm::RationalFunction>>>(m, "SparseParametricDtmc", "pDTMC in sparse representation", modelRatFunc)
     ;
-    py::class_<storm::models::sparse::Mdp<storm::RationalFunction>, std::shared_ptr<storm::models::sparse::Mdp<storm::RationalFunction>>>(m, "SparseParametricMdp", "pMDP in sparse representation", py::base<storm::models::sparse::Model<storm::RationalFunction>>())
+    py::class_<storm::models::sparse::Mdp<storm::RationalFunction>, std::shared_ptr<storm::models::sparse::Mdp<storm::RationalFunction>>>(m, "SparseParametricMdp", "pMDP in sparse representation", modelRatFunc)
     ;
 
 }