diff --git a/src/models/sparse/Model.cpp b/src/models/sparse/Model.cpp
index a1e71c0b7..e30965998 100644
--- a/src/models/sparse/Model.cpp
+++ b/src/models/sparse/Model.cpp
@@ -320,7 +320,7 @@ namespace storm {
                 return this->rewardModels;
             }
 
-            std::set<storm::Variable> getProbabilityParameters(Model<storm::RationalNumber> const& model) {
+            std::set<storm::Variable> getProbabilityParameters(Model<storm::RationalFunction> const& model) {
                 return storm::storage::getVariables(model.getTransitionMatrix());
             }
             
diff --git a/src/storage/SparseMatrix.cpp b/src/storage/SparseMatrix.cpp
index 1bc2f9af0..253609210 100644
--- a/src/storage/SparseMatrix.cpp
+++ b/src/storage/SparseMatrix.cpp
@@ -1208,6 +1208,19 @@ namespace storm {
             return result;
         }
         
+        
+#ifdef STORM_HAVE_CARL
+        std::set<storm::Variable> getVariables(SparseMatrix<storm::RationalFunction> const& matrix)
+        {
+            std::set<storm::Variable> result;
+            for(auto const& entry : matrix) {
+                entry.getValue().gatherVariables(result);
+            }
+            return result;
+        }
+        
+#endif
+        
         // Explicitly instantiate the entry, builder and the matrix.
         // double
         template class MatrixEntry<typename SparseMatrix<double>::index_type, double>;
diff --git a/src/storage/SparseMatrix.h b/src/storage/SparseMatrix.h
index 21d675cab..f9d9916c4 100644
--- a/src/storage/SparseMatrix.h
+++ b/src/storage/SparseMatrix.h
@@ -8,7 +8,7 @@
 #include <iterator>
 
 #include "src/utility/OsDetection.h"
-
+#include "src/adapters/CarlAdapter.h"
 #include <boost/functional/hash.hpp>
 
 // Forward declaration for adapter classes.
@@ -970,14 +970,10 @@ namespace storm {
             
         };
         
-        std::set<storm::Variable> getVariables(SparseMatrix<storm::RationalFunction> const& matrix) {
-            std::set<storm::Variable> result;
-            for(auto const& entry : matrix) {
-                entry.probability.gatherVariables(result);
-            }
-            return result;
-        }
-
+#ifdef STORM_HAVE_CARL
+        std::set<storm::Variable> getVariables(SparseMatrix<storm::RationalFunction> const& matrix);
+#endif
+        
     } // namespace storage
 } // namespace storm