diff --git a/src/importer/sources/bottles_source.py b/src/importer/sources/bottles_source.py
index 4abc3f3..9fa1849 100644
--- a/src/importer/sources/bottles_source.py
+++ b/src/importer/sources/bottles_source.py
@@ -1,6 +1,6 @@
 from pathlib import Path
 from time import time
-from typing import Optional
+from typing import Optional, Generator
 
 import yaml
 
@@ -14,7 +14,7 @@ from src.utils.save_cover import resize_cover, save_cover
 class BottlesSourceIterator(SourceIterator):
     source: "BottlesSource"
 
-    def generator_builder(self) -> Optional[Game]:
+    def generator_builder(self) -> Generator[Optional[Game], None, None]:
         """Generator method producing games"""
 
         data = (self.source.location / "library.yml").read_text("utf-8")
diff --git a/src/importer/sources/heroic_source.py b/src/importer/sources/heroic_source.py
index 3515125..c6ef498 100644
--- a/src/importer/sources/heroic_source.py
+++ b/src/importer/sources/heroic_source.py
@@ -4,7 +4,7 @@ from hashlib import sha256
 from json import JSONDecodeError
 from pathlib import Path
 from time import time
-from typing import Optional, TypedDict
+from typing import Optional, TypedDict, Generator
 
 from src import shared
 from src.game import Game
@@ -85,7 +85,7 @@ class HeroicSourceIterator(SourceIterator):
 
         return Game(values, allow_side_effects=False)
 
-    def generator_builder(self):
+    def generator_builder(self) -> Generator[Optional[Game], None, None]:
         """Generator method producing games from all the Heroic sub-sources"""
 
         for sub_source in self.sub_sources.values():
diff --git a/src/importer/sources/lutris_source.py b/src/importer/sources/lutris_source.py
index d9b8c35..63e3344 100644
--- a/src/importer/sources/lutris_source.py
+++ b/src/importer/sources/lutris_source.py
@@ -1,6 +1,6 @@
 from sqlite3 import connect
 from time import time
-from typing import Optional
+from typing import Optional, Generator
 
 from src import shared
 from src.game import Game
@@ -12,7 +12,7 @@ from src.utils.save_cover import resize_cover, save_cover
 class LutrisSourceIterator(SourceIterator):
     source: "LutrisSource"
 
-    def generator_builder(self) -> Optional[Game]:
+    def generator_builder(self) -> Generator[Optional[Game], None, None]:
         """Generator method producing games"""
 
         # Query the database
diff --git a/src/importer/sources/steam_source.py b/src/importer/sources/steam_source.py
index fbde1be..e93b9f3 100644
--- a/src/importer/sources/steam_source.py
+++ b/src/importer/sources/steam_source.py
@@ -1,7 +1,7 @@
 import re
 from pathlib import Path
 from time import time
-from typing import Iterable, Optional
+from typing import Iterable, Optional, Generator
 
 from src import shared
 from src.game import Game
@@ -44,7 +44,7 @@ class SteamSourceIterator(SourceIterator):
             )
         return manifests
 
-    def generator_builder(self) -> Optional[Game]:
+    def generator_builder(self) -> Generator[Optional[Game], None, None]:
         """Generator method producing games"""
         appid_cache = set()
         manifests = self.get_manifests()