diff --git a/ruff-strict-pep8.toml b/ruff-strict-pep8.toml
index 2cd1a8c895..c69667c85e 100644
--- a/ruff-strict-pep8.toml
+++ b/ruff-strict-pep8.toml
@@ -29,7 +29,7 @@ ignore = [
 ]
 select = [
     'E', 'F', 'I', 'W', 'INT',
-    'Q', 'UP', 'YTT', 'TID', 'C4', 'COM818', 'PIE',
+    'Q', 'UP', 'YTT', 'TID', 'C4', 'COM818', 'PIE', 'RET501',
     'RUF',  # nota: RUF can flag many unsolicited errors
     # preview rules
     'RUF051', 'RUF056',  # useless dict operation
@@ -43,19 +43,24 @@ select = [
 ]
 unfixable = ['PIE794']
 
+
 [lint.per-file-ignores]
 "recipes/*" = ['UP']
 "manual/plugin_examples/*" = ['UP']
 "setup/commands.py" = ['RUF022']
 "src/calibre/*" = ['UP031']
+"src/calibre/customize/__init__.py" = ['RET501']
+"src/calibre/devices/interface.py" = ['RET501']
 "src/calibre/devices/kobo/driver.py" = ['E116']
 "src/calibre/ebooks/unihandecode/*codepoints.py" = ['E501']
 "src/calibre/ebooks/metadata/sources/*" = ['UP']
+"src/calibre/ebooks/metadata/sources/base.py" = ['RET501']
 "src/calibre/ebooks/pdf/reflow.py" = ['E114']
 "src/calibre/gui2/store/stores/*" = ['UP']
 "src/calibre/gui2/tts/manager.py" = ['UP037']
 "src/calibre/utils/copy_files.py" = ['UP037']
 "src/calibre/utils/smartypants.py" = ['RUF039', 'RUF055']
+"src/calibre/web/feeds/news.py" = ['RET501']
 "src/qt/*.py" = ['I', 'E302']
 "src/qt/*.pyi" = ['I']
 
diff --git a/src/calibre/ebooks/mobi/debug/mobi6.py b/src/calibre/ebooks/mobi/debug/mobi6.py
index 50ecbddb44..8e0bfec64c 100644
--- a/src/calibre/ebooks/mobi/debug/mobi6.py
+++ b/src/calibre/ebooks/mobi/debug/mobi6.py
@@ -405,7 +405,7 @@ class IndexRecord:  # {{{
 
     def get_parent(self, index):
         if index.depth < 1:
-            return None
+            return
         parent_depth = index.depth - 1
         for p in self.indices:
             if p.depth != parent_depth:
diff --git a/src/calibre/gui2/library/delegates.py b/src/calibre/gui2/library/delegates.py
index ed0cc8a723..324fa95572 100644
--- a/src/calibre/gui2/library/delegates.py
+++ b/src/calibre/gui2/library/delegates.py
@@ -610,7 +610,7 @@ class CcLongTextDelegate(StyledItemDelegate):  # {{{
         d = PlainTextDialog(parent, text, column_name=m.custom_columns[col]['name'])
         if d.exec() == QDialog.DialogCode.Accepted:
             m.setData(index, d.text, Qt.ItemDataRole.EditRole)
-        return None
+        return
 
     def setModelData(self, editor, model, index):
         model.setData(index, (editor.textbox.html), Qt.ItemDataRole.EditRole)
@@ -665,7 +665,7 @@ class CcMarkdownDelegate(StyledItemDelegate):  # {{{
                                base_url=base_url)
         if d.exec() == QDialog.DialogCode.Accepted:
             m.setData(index, (d.text), Qt.ItemDataRole.EditRole)
-        return None
+        return
 
     def setModelData(self, editor, model, index):
         model.setData(index, (editor.textbox.html), Qt.ItemDataRole.EditRole)
@@ -816,7 +816,7 @@ class CcCommentsDelegate(StyledItemDelegate):  # {{{
         d = editor.exec()
         if d:
             m.setData(index, (editor.textbox.html), Qt.ItemDataRole.EditRole)
-        return None
+        return
 
     def setModelData(self, editor, model, index):
         model.setData(index, (editor.textbox.html), Qt.ItemDataRole.EditRole)