--- a/k3dsdk/ngui/main_document_window.cpp
+++ b/k3dsdk/ngui/main_document_window.cpp
@@ -1371,7 +1371,7 @@
 			Gtk::HBox import_box(false, 5);
 			Gtk::Label import_label(_("Choose import plugin:"));
 
-			Gtk::ComboBox import_combo(model);
+			Gtk::ComboBox import_combo((Glib::RefPtr<Gtk::TreeModel> &) model);
 			import_combo.pack_start(columns.icon, false);
 			import_combo.pack_start(columns.label);
 			import_combo.set_active(0);
@@ -1461,7 +1461,7 @@
 			Gtk::HBox export_box(false, 5);
 			Gtk::Label export_label(_("Choose export plugin:"));
 
-			Gtk::ComboBox export_combo(model);
+			Gtk::ComboBox export_combo((Glib::RefPtr<Gtk::TreeModel> &) model);
 			export_combo.pack_start(columns.icon, false);
 			export_combo.pack_start(columns.label);
 			export_combo.set_active(0);
--- a/k3dsdk/ngui/render.cpp
+++ b/k3dsdk/ngui/render.cpp
@@ -169,7 +169,7 @@
 		row[columns.separator] = false;
 	}
 
-	Gtk::ComboBox combo(model);
+	Gtk::ComboBox combo((Glib::RefPtr<Gtk::TreeModel> &) model);
 
 	combo.pack_start(columns.icon, false);
 
@@ -295,7 +295,7 @@
 		row[columns.separator] = false;
 	}
 
-	Gtk::ComboBox combo(model);
+	Gtk::ComboBox combo((Glib::RefPtr<Gtk::TreeModel> &) model);
 
 	combo.pack_start(columns.icon, false);