diff --git a/noxfile.py b/noxfile.py
index f056b7a..17d9d37 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -1,4 +1,4 @@
-import nox
+import nox  # type: ignore
 
 
 @nox.session(python=["3.7", "3.8", "3.9"])
diff --git a/src/habitmove/__init__.py b/src/habitmove/__init__.py
index fcbc880..6c60766 100644
--- a/src/habitmove/__init__.py
+++ b/src/habitmove/__init__.py
@@ -4,6 +4,6 @@ import sys
 try:
     from importlib.metadata import version as metadata_version
 except ImportError:
-    from importlib_metadata import version as metadata_version
+    from importlib_metadata import version as metadata_version  # type: ignore
 
 __version__ = str(metadata_version(__name__))
diff --git a/src/habitmove/repetitions.py b/src/habitmove/repetitions.py
index 0d1ffa9..63ce416 100644
--- a/src/habitmove/repetitions.py
+++ b/src/habitmove/repetitions.py
@@ -55,10 +55,11 @@ def habit_list_add_ids(c: sqlite3.Cursor, habitlist: list[Habit]) -> dict[int, H
     :return habit_id_dict: The habit collection as a dict with the keys
                                  consisting of the habit's sqlite database ID.
     """
-    with_id = {}
+    with_id: dict[int, Habit] = {}
     for h in habitlist:
         sql_id = fetch_habit_id(c, h.uuid or "")
-        with_id[sql_id] = h
+        if sql_id is not None:
+            with_id[sql_id] = h
 
     return with_id
 
@@ -74,6 +75,8 @@ def fetch_habit_id(cursor: sqlite3.Cursor, uuid: str) -> Optional[int]:
     if id is not None:
         return id[0]
 
+    return None
+
 
 def add_to_database(
     cursor: sqlite3.Cursor, habits: dict[int, Habit], repetition: Repetition