diff --git a/Applications/ApplicationsLib/ProjectData.h b/Applications/ApplicationsLib/ProjectData.h
index 356f8d4990b3757bcb1df7c1458314a025fb9c5e..ebd0f4d02e9fb83f8cdcfadd1a8fd0856f1c18dc 100644
--- a/Applications/ApplicationsLib/ProjectData.h
+++ b/Applications/ApplicationsLib/ProjectData.h
@@ -116,7 +116,6 @@ private:
     void parseChemicalSystem(boost::optional<BaseLib::ConfigTree> const& config,
                              const std::string& output_directory);
 
-    std::unique_ptr<MaterialPropertyLib::Medium> _medium;
     std::vector<std::unique_ptr<MeshLib::Mesh>> _mesh_vec;
     std::vector<std::unique_ptr<ProcessLib::Process>> _processes;
     std::vector<ProcessLib::ProcessVariable> _process_variables;