diff --git a/.mypy.ini b/.mypy.ini
index 6ba52ee64..da2daea54 100644
--- a/.mypy.ini
+++ b/.mypy.ini
@@ -80,6 +80,12 @@ strict_optional = True
 strict_optional = True
 [mypy-aqt.switch]
 strict_optional = True
+[mypy-aqt.debug_console]
+strict_optional = True
+[mypy-aqt.emptycards]
+strict_optional = True
+[mypy-aqt.flags]
+strict_optional = True
 [mypy-anki.scheduler.base]
 strict_optional = True
 [mypy-anki._backend.rsbridge]
diff --git a/qt/aqt/debug_console.py b/qt/aqt/debug_console.py
index 76fead38b..2ad9843db 100644
--- a/qt/aqt/debug_console.py
+++ b/qt/aqt/debug_console.py
@@ -196,6 +196,7 @@ class DebugConsole(QDialog):
 
     def _on_context_menu(self, text_edit: QPlainTextEdit) -> None:
         menu = text_edit.createStandardContextMenu()
+        assert menu is not None
         menu.addSeparator()
         for action in self._actions():
             entry = menu.addAction(action.name)
@@ -227,7 +228,7 @@ class DebugConsole(QDialog):
             sys.stderr = self._oldStderr
             sys.stdout = self._oldStdout
 
-    def _card_repr(self, card: anki.cards.Card) -> None:
+    def _card_repr(self, card: anki.cards.Card | None) -> None:
         import copy
         import pprint
 
@@ -316,6 +317,7 @@ class DebugConsole(QDialog):
             )
             self._log.appendPlainText(to_append)
         slider = self._log.verticalScrollBar()
+        assert slider is not None
         slider.setValue(slider.maximum())
         self._log.ensureCursorVisible()
 
diff --git a/qt/aqt/emptycards.py b/qt/aqt/emptycards.py
index 378aa09c3..78436239e 100644
--- a/qt/aqt/emptycards.py
+++ b/qt/aqt/emptycards.py
@@ -63,7 +63,7 @@ class EmptyCardsDialog(QDialog):
 
         def on_finished(code: Any) -> None:
             self.form.webview.cleanup()
-            self.form.webview = None
+            self.form.webview = None  # type: ignore
             saveGeom(self, "emptycards")
 
         qconnect(self.finished, on_finished)
@@ -71,6 +71,7 @@ class EmptyCardsDialog(QDialog):
         self._delete_button = self.form.buttonBox.addButton(
             tr.empty_cards_delete_button(), QDialogButtonBox.ButtonRole.ActionRole
         )
+        assert self._delete_button is not None
         self._delete_button.setAutoDefault(False)
         qconnect(self._delete_button.clicked, self._on_delete)
 
diff --git a/qt/aqt/flags.py b/qt/aqt/flags.py
index 5373206ab..7a1b9aef1 100644
--- a/qt/aqt/flags.py
+++ b/qt/aqt/flags.py
@@ -34,11 +34,11 @@ class Flag:
 class FlagManager:
     def __init__(self, mw: aqt.main.AnkiQt) -> None:
         self.mw = mw
-        self._flags: list[Flag] | None = None
+        self._flags: list[Flag] = []
 
     def all(self) -> list[Flag]:
         """Return a list of all flags."""
-        if self._flags is None:
+        if not self._flags:
             self._load_flags()
         return self._flags
 
@@ -57,7 +57,7 @@ class FlagManager:
 
     def require_refresh(self) -> None:
         "Discard cached labels."
-        self._flags = None
+        self._flags = []
 
     def _load_flags(self) -> None:
         labels = cast(dict[str, str], self.mw.col.get_config("flagLabels", {}))