diff --git a/GUI/Model/To/DomainSimulationBuilder.h b/GUI/Model/To/DomainSimulationBuilder.h
index 94b18d236689f8cdd26509fab4c17760408b1c4d..cac02744e7a5e5cb8e97ef2aebb4a4741224589c 100644
--- a/GUI/Model/To/DomainSimulationBuilder.h
+++ b/GUI/Model/To/DomainSimulationBuilder.h
@@ -30,7 +30,7 @@ namespace GUI::Model::DomainSimulationBuilder {
 
 std::unique_ptr<ISimulation> createSimulation(const MultiLayerItem* sampleItem,
                                               const InstrumentItem* instrumentItem,
-                                              const SimulationOptionsItem* optionsItem = nullptr);
+                                              const SimulationOptionsItem* optionsItem);
 } // namespace GUI::Model::DomainSimulationBuilder
 
 #endif // BORNAGAIN_GUI_MODEL_TO_DOMAINSIMULATIONBUILDER_H
diff --git a/GUI/View/Script/PythonScriptWidget.h b/GUI/View/Script/PythonScriptWidget.h
index 6acfca8101ab1ae7f1becac7ae1f0f2e090751a1..c534341d5b390bd4bb22dfe616a239683dad0b13 100644
--- a/GUI/View/Script/PythonScriptWidget.h
+++ b/GUI/View/Script/PythonScriptWidget.h
@@ -35,7 +35,7 @@ public:
 
     void generatePythonScript(const MultiLayerItem* sampleItem,
                               const InstrumentItem* instrumentItem,
-                              const SimulationOptionsItem* optionItem = nullptr,
+                              const SimulationOptionsItem* optionItem,
                               const QString& outputDir = "");
 
 private slots: