diff --git a/pylib/anki/rsbackend.py b/pylib/anki/rsbackend.py
index def276f30..b5f10f8dd 100644
--- a/pylib/anki/rsbackend.py
+++ b/pylib/anki/rsbackend.py
@@ -178,7 +178,9 @@ def proto_progress_to_native(progress: pb.Progress) -> Progress:
 
 
 class RustBackend:
-    def __init__(self, col_path: str, media_folder_path: str, media_db_path: str):
+    def __init__(
+        self, col_path: str, media_folder_path: str, media_db_path: str
+    ) -> None:
         ftl_folder = os.path.join(anki.lang.locale_folder, "fluent")
         init_msg = pb.BackendInit(
             collection_path=col_path,
@@ -340,7 +342,7 @@ class RustBackend:
             )
         ).format_time_span
 
-    def studied_today(self, cards: int, seconds: float,) -> str:
+    def studied_today(self, cards: int, seconds: float) -> str:
         return self._run_command(
             pb.BackendInput(
                 studied_today=pb.StudiedTodayIn(cards=cards, seconds=seconds)
@@ -376,7 +378,7 @@ class I18nBackend:
         )
         self._backend = ankirspy.open_i18n(init_msg.SerializeToString())
 
-    def translate(self, key: TR, **kwargs: Union[str, int, float]):
+    def translate(self, key: TR, **kwargs: Union[str, int, float]) -> str:
         return self._backend.translate(
             translate_string_in(key, **kwargs).SerializeToString()
         )