diff --git a/src/libslic3r/AppConfig.hpp b/src/libslic3r/AppConfig.hpp
index 418f3427b..cd0f1a5ae 100644
--- a/src/libslic3r/AppConfig.hpp
+++ b/src/libslic3r/AppConfig.hpp
@@ -100,7 +100,7 @@ public:
 	bool                has_section(const std::string &section) const
 		{ return m_storage.find(section) != m_storage.end(); }
 	const std::map<std::string, std::string>& get_section(const std::string &section) const
-		{ return m_storage.find(section)->second; }
+		{ auto it = m_storage.find(section); assert(it != m_storage.end()); return it->second; }
 	void set_section(const std::string &section, const std::map<std::string, std::string>& data)
 		{ m_storage[section] = data; }
 	void 				clear_section(const std::string &section)
diff --git a/src/slic3r/GUI/ConfigWizard.cpp b/src/slic3r/GUI/ConfigWizard.cpp
index 66b27995f..dadf5d8ca 100644
--- a/src/slic3r/GUI/ConfigWizard.cpp
+++ b/src/slic3r/GUI/ConfigWizard.cpp
@@ -2720,8 +2720,11 @@ bool ConfigWizard::priv::apply_config(AppConfig *app_config, PresetBundle *prese
                 return false;
         }
         else {
-            bool is_filaments_changed = app_config->get_section(AppConfig::SECTION_FILAMENTS) != appconfig_new.get_section(AppConfig::SECTION_FILAMENTS);
-            bool is_sla_materials_changed = app_config->get_section(AppConfig::SECTION_MATERIALS) != appconfig_new.get_section(AppConfig::SECTION_MATERIALS);
+            auto changed = [app_config, &appconfig_new = std::as_const(this->appconfig_new)](const std::string& section_name) {
+                return (app_config->has_section(section_name) ? app_config->get_section(section_name) : std::map<std::string, std::string>()) != appconfig_new.get_section(section_name);
+            };
+            bool is_filaments_changed     = changed(AppConfig::SECTION_FILAMENTS);
+            bool is_sla_materials_changed = changed(AppConfig::SECTION_MATERIALS);
             if ((check_unsaved_preset_changes = is_filaments_changed || is_sla_materials_changed)) {
                 header = is_filaments_changed ? _L("Some filaments were uninstalled.") : _L("Some SLA materials were uninstalled.");
                 if (!wxGetApp().check_and_keep_current_preset_changes(caption, header, act_btns, &apply_keeped_changes))