diff --git a/src/calibre/gui2/actions/catalog.py b/src/calibre/gui2/actions/catalog.py
index 67cf726202..8430b69dfb 100644
--- a/src/calibre/gui2/actions/catalog.py
+++ b/src/calibre/gui2/actions/catalog.py
@@ -85,7 +85,7 @@ class GenerateCatalogAction(InterfaceAction):
             id = self.gui.library_view.model().add_catalog(job.catalog_file_path, job.catalog_title)
             self.gui.library_view.model().beginResetModel(), self.gui.library_view.model().endResetModel()
             if job.catalog_sync:
-                sync = dynamic.get('catalogs_to_be_synced', set([]))
+                sync = dynamic.get('catalogs_to_be_synced', set())
                 sync.add(id)
                 dynamic.set('catalogs_to_be_synced', sync)
         self.gui.status_bar.show_message(_('Catalog generated.'), 3000)
diff --git a/src/calibre/gui2/actions/delete.py b/src/calibre/gui2/actions/delete.py
index 7a04addcb3..4e6317b28a 100644
--- a/src/calibre/gui2/actions/delete.py
+++ b/src/calibre/gui2/actions/delete.py
@@ -165,7 +165,7 @@ class DeleteAction(InterfaceAction):
         if not rows or len(rows) == 0:
             d = error_dialog(self.gui, err_title, _('No book selected'))
             d.exec_()
-            return set([])
+            return set()
         return set(map(self.gui.library_view.model().id, rows))
 
     def remove_format_by_id(self, book_id, fmt):
diff --git a/src/calibre/gui2/actions/view.py b/src/calibre/gui2/actions/view.py
index 9ad6954d28..c5fcfbeaae 100644
--- a/src/calibre/gui2/actions/view.py
+++ b/src/calibre/gui2/actions/view.py
@@ -166,7 +166,7 @@ class ViewAction(InterfaceAction):
         rows = [r.row() for r in rows]
         book_ids = [db.id(r) for r in rows]
         formats = [[x.upper() for x in db.new_api.formats(book_id)] for book_id in book_ids]
-        all_fmts = set([])
+        all_fmts = set()
         for x in formats:
             if x:
                 for f in x:
diff --git a/src/calibre/gui2/device.py b/src/calibre/gui2/device.py
index bd0ba2e47d..ef0f0117d6 100644
--- a/src/calibre/gui2/device.py
+++ b/src/calibre/gui2/device.py
@@ -1343,7 +1343,7 @@ class DeviceMixin(object):  # {{{
                         self.iactions['Convert Books'].auto_convert_catalogs(auto, format)
             files = [f for f in files if f is not None]
             if not files:
-                dynamic.set('catalogs_to_be_synced', set([]))
+                dynamic.set('catalogs_to_be_synced', set())
                 return
             metadata = self.library_view.model().metadata_for(ids)
             names = []
@@ -1355,7 +1355,7 @@ class DeviceMixin(object):  # {{{
                 names.append('%s_%d%s'%(prefix, id,
                     os.path.splitext(files[-1])[1]))
                 self.update_thumbnail(mi)
-            dynamic.set('catalogs_to_be_synced', set([]))
+            dynamic.set('catalogs_to_be_synced', set())
             if files:
                 remove = []
                 space = {self.location_manager.free[0] : None,