diff --git a/kiwi_scp/commands/cli.py b/kiwi_scp/commands/cli.py
index acd09b6..cc4cb04 100644
--- a/kiwi_scp/commands/cli.py
+++ b/kiwi_scp/commands/cli.py
@@ -130,7 +130,7 @@ class KiwiCommand:
         return answer == "yes"
 
     @classmethod
-    def run(cls, instance: Instance, project_names: List[str], service_names: List[str], **kwargs):
+    def run(cls, instance: Instance, project_names: List[str], service_names: List[str], **kwargs) -> None:
 
         _logger.debug(f"{instance.directory!r}: {project_names!r}, {service_names!r}")
 
diff --git a/kiwi_scp/scripts/kiwi.py b/kiwi_scp/scripts/kiwi.py
index b64bfef..764c335 100644
--- a/kiwi_scp/scripts/kiwi.py
+++ b/kiwi_scp/scripts/kiwi.py
@@ -6,7 +6,7 @@ from kiwi_scp.commands.cli import KiwiCLI
 
 
 @click.command(cls=KiwiCLI)
-def main():
+def main() -> None:
     """kiwi is the simple tool for managing container servers."""
 
     verbosity = 0
diff --git a/kiwi_scp/yaml.py b/kiwi_scp/yaml.py
index 972b12d..1b8729c 100644
--- a/kiwi_scp/yaml.py
+++ b/kiwi_scp/yaml.py
@@ -8,7 +8,7 @@ from ._constants import HEADER_KIWI_CONF_NAME
 
 
 class YAML(ruamel.yaml.YAML):
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args, **kwargs) -> None:
         super().__init__(*args, **kwargs)
         self.indent(offset=2)