diff --git a/src/gardenlinux/apt/debsource.py b/src/gardenlinux/apt/debsource.py
index aeaf733e..aacfcb76 100644
--- a/src/gardenlinux/apt/debsource.py
+++ b/src/gardenlinux/apt/debsource.py
@@ -106,7 +106,7 @@ def read(self, f: TextIO) -> None:
 
         self._set_source(parsed_source, parsed_version)
 
-    def _set_source(self, source: str, version: str) -> None:
+    def _set_source(self, source: str | None, version: str | None) -> None:
         """
         Sets the dict value based on the given source key.
 
diff --git a/src/gardenlinux/apt/package_repo_info.py b/src/gardenlinux/apt/package_repo_info.py
index 72428849..5342ed18 100644
--- a/src/gardenlinux/apt/package_repo_info.py
+++ b/src/gardenlinux/apt/package_repo_info.py
@@ -71,7 +71,7 @@ def get_packages_versions(self) -> list[tuple[str, str]]:
 
 def compare_gardenlinux_repo_version(
     version_a: str, version_b: str
-) -> list[tuple[str, str, str]]:
+) -> list[tuple[str, str | None, str | None]]:
     """
     Compares differences between repository versions given.
 
@@ -89,7 +89,7 @@ def compare_gardenlinux_repo_version(
 
 def compare_repo(
     a: GardenLinuxRepo, b: GardenLinuxRepo, available_in_both: Optional[bool] = False
-) -> list[tuple[str, str, str]]:
+) -> list[tuple[str, str | None, str | None]]:
     """
     Compares differences between repositories given.