diff --git a/src/calibre/gui2/preferences/behavior.py b/src/calibre/gui2/preferences/behavior.py
index 9ff97c99e1..8de1b43682 100644
--- a/src/calibre/gui2/preferences/behavior.py
+++ b/src/calibre/gui2/preferences/behavior.py
@@ -45,7 +45,7 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
         r('upload_news_to_device', config)
         r('delete_news_from_library_on_upload', config)
 
-        output_formats = list(sorted(available_output_formats()))
+        output_formats = sorted(available_output_formats())
         output_formats.remove('oeb')
         choices = [(x.upper(), x) for x in output_formats]
         r('output_format', prefs, choices=choices, setting=OutputFormatSetting)
diff --git a/src/calibre/gui2/preferences/look_feel.py b/src/calibre/gui2/preferences/look_feel.py
index 78a6828240..c6d5abe7b9 100644
--- a/src/calibre/gui2/preferences/look_feel.py
+++ b/src/calibre/gui2/preferences/look_feel.py
@@ -496,7 +496,7 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
         choices |= {'search'}
         self.opt_categories_using_hierarchy.update_items_cache(choices)
         r('categories_using_hierarchy', db.prefs, setting=CommaSeparatedList,
-          choices=sorted(list(choices), key=sort_key))
+          choices=sorted(choices, key=sort_key))
 
         fm = db.field_metadata
         choices = sorted(((fm[k]['name'], k) for k in fm.displayable_field_keys() if fm[k]['name']),