diff --git a/kiwi_scp/config.py b/kiwi_scp/config.py
index e78b6cd..08c4a3a 100644
--- a/kiwi_scp/config.py
+++ b/kiwi_scp/config.py
@@ -1,7 +1,7 @@
 import functools
 from ipaddress import IPv4Network
 from pathlib import Path
-from typing import Optional, Dict, List, Any, TextIO
+from typing import Optional, Dict, List, Any, TextIO, Tuple
 
 from pydantic import BaseModel, constr, root_validator, validator
 
@@ -55,7 +55,7 @@ class ProjectConfig(BaseModel):
 
     @validator("override_storage", pre=True)
     @classmethod
-    def unify_storage(cls, value):
+    def unify_storage(cls, value) -> Dict[str, Any]:
         """parse different storage notations"""
 
         if value is None or isinstance(value, dict):
@@ -135,7 +135,7 @@ class KiwiConfig(BaseModel):
 
     @classmethod
     @functools.lru_cache(maxsize=5)
-    def from_directory(cls, directory: Path):
+    def from_directory(cls, directory: Path) -> "KiwiConfig":
         """parses an actual kiwi.yml from disk (cached)"""
 
         try:
@@ -148,7 +148,7 @@ class KiwiConfig(BaseModel):
 
     @classmethod
     @functools.lru_cache(maxsize=1)
-    def from_default(cls):
+    def from_default(cls) -> "KiwiConfig":
         """returns the default config (cached)"""
 
         return cls()
@@ -268,7 +268,7 @@ class KiwiConfig(BaseModel):
     def unify_environment(cls, value) -> Dict[str, Optional[str]]:
         """parse different environment notations"""
 
-        def parse_str(var_val: Any) -> (str, Optional[str]):
+        def parse_str(var_val: Any) -> Tuple[str, Optional[str]]:
             """parse a "<variable>=<value>" string"""
 
             try:
@@ -311,7 +311,7 @@ class KiwiConfig(BaseModel):
 
     @validator("storage", pre=True)
     @classmethod
-    def unify_storage(cls, value):
+    def unify_storage(cls, value) -> Dict[str, Any]:
         """parse different storage notations"""
 
         if value is None:
@@ -336,7 +336,7 @@ class KiwiConfig(BaseModel):
 
     @validator("network", pre=True)
     @classmethod
-    def unify_network(cls, value):
+    def unify_network(cls, value) -> Dict[str, Any]:
         """parse different network notations"""
 
         if value is None:
diff --git a/kiwi_scp/instance.py b/kiwi_scp/instance.py
index 84f7c22..7b358b0 100644
--- a/kiwi_scp/instance.py
+++ b/kiwi_scp/instance.py
@@ -46,7 +46,7 @@ class Services:
     def __bool__(self) -> bool:
         return bool(self.content)
 
-    def filter_existing(self, service_names: List[str]):
+    def filter_existing(self, service_names: List[str]) -> "Services":
         return Services([
             service
             for service in self.content
diff --git a/kiwi_scp/misc.py b/kiwi_scp/misc.py
index eb2ad3b..b38d4a0 100644
--- a/kiwi_scp/misc.py
+++ b/kiwi_scp/misc.py
@@ -23,7 +23,7 @@ class YAML(ruamel.yaml.YAML):
             return stream.getvalue()
 
     @staticmethod
-    def _format_kiwi_yml(yml_string: str):
+    def _format_kiwi_yml(yml_string: str) -> str:
         # insert newline before every main key
         yml_string = re.sub(r'^(\S)', r'\n\1', yml_string, flags=re.MULTILINE)
 
diff --git a/kiwi_scp/rootkit.py b/kiwi_scp/rootkit.py
index adef3f1..c1a42da 100644
--- a/kiwi_scp/rootkit.py
+++ b/kiwi_scp/rootkit.py
@@ -67,9 +67,9 @@ class Rootkit:
                     f"{IMAGES_DIRECTORY_NAME}"
                 ], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
 
-    def run(self, process_args, **kwargs):
+    def run(self, process_args, **kwargs) -> Optional[subprocess.CompletedProcess]:
         self.__build_image()
-        DOCKER_EXE.run([
+        return DOCKER_EXE.run([
             'run', '--rm',
             '-v', '/:/mnt',
             '-u', 'root',