diff --git a/src/libslic3r/Config.cpp b/src/libslic3r/Config.cpp
index a7c8cdfbc8..8ac538034e 100644
--- a/src/libslic3r/Config.cpp
+++ b/src/libslic3r/Config.cpp
@@ -335,12 +335,9 @@ void ConfigDef::finalize()
         if (def.type == coEnum) {
             assert(def.enum_def);
             assert(def.enum_def->is_valid_closed_enum());
-            assert(def.gui_type != ConfigOptionDef::GUIType::i_enum_open && 
-                   def.gui_type != ConfigOptionDef::GUIType::f_enum_open && 
-                   def.gui_type != ConfigOptionDef::GUIType::select_open);
+            assert(! def.is_gui_type_enum_open());
             def.enum_def->finalize_closed_enum();
-        } else if (def.gui_type == ConfigOptionDef::GUIType::i_enum_open || def.gui_type == ConfigOptionDef::GUIType::f_enum_open ||
-                   def.gui_type == ConfigOptionDef::GUIType::select_open) {
+        } else if (def.is_gui_type_enum_open()) {
             assert(def.enum_def);
             assert(def.enum_def->is_valid_open_enum());
             assert(def.gui_type != ConfigOptionDef::GUIType::i_enum_open || def.type == coInt || def.type == coInts);
@@ -427,7 +424,7 @@ std::ostream& ConfigDef::print_cli_help(std::ostream& out, bool show_defaults, s
                 descr += " (";
                 if (!def.sidetext.empty()) {
                     descr += def.sidetext + ", ";
-                } else if (def.enum_def->has_values()) {
+                } else if (def.enum_def && def.enum_def->has_values()) {
                     descr += boost::algorithm::join(def.enum_def->values(), ", ") + "; ";
                 }
                 descr += "default: " + def.default_value->serialize() + ")";
diff --git a/src/libslic3r/Config.hpp b/src/libslic3r/Config.hpp
index b6320b126b..b41ed764c3 100644
--- a/src/libslic3r/Config.hpp
+++ b/src/libslic3r/Config.hpp
@@ -1836,6 +1836,8 @@ public:
         // Close parameter, string value could be one of the list values.
         select_close,
     };
+    static bool is_gui_type_enum_open(const GUIType gui_type) 
+        { return gui_type == ConfigOptionDef::GUIType::i_enum_open || gui_type == ConfigOptionDef::GUIType::f_enum_open || gui_type == ConfigOptionDef::GUIType::select_open; }
 
 	// Identifier of this option. It is stored here so that it is accessible through the by_serialization_key_ordinal map.
 	t_config_option_key 				opt_key;
@@ -1923,6 +1925,7 @@ public:
     // Special values - "i_enum_open", "f_enum_open" to provide combo box for int or float selection,
     // "select_open" - to open a selection dialog (currently only a serial port selection).
     GUIType                             gui_type { GUIType::undefined };
+    bool                                is_gui_type_enum_open() const { return is_gui_type_enum_open(this->gui_type); }
     // Usually empty. Otherwise "serialized" or "show_value"
     // The flags may be combined.
     // "serialized" - vector valued option is entered in a single edit field. Values are separated by a semicolon.