diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index 482126c41b3..dafec791147 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -32,6 +32,7 @@ jobs:
           - "nav2_common"
           - "nav2_bringup"
           - "nav2_collision_monitor"
+          - "nav2_costmap_2d"
     steps:
     - uses: actions/checkout@v4
 
diff --git a/nav2_costmap_2d/test/integration/costmap_tests_launch.py b/nav2_costmap_2d/test/integration/costmap_tests_launch.py
index 5980f8f699b..d1bec18587f 100755
--- a/nav2_costmap_2d/test/integration/costmap_tests_launch.py
+++ b/nav2_costmap_2d/test/integration/costmap_tests_launch.py
@@ -24,9 +24,9 @@
 from launch_testing.legacy import LaunchTestService
 
 
-def main(argv=sys.argv[1:]):
+def main(argv: list[str] = sys.argv[1:]) -> LaunchTestService:
     launchFile = os.path.join(
-        os.getenv('TEST_LAUNCH_DIR'), 'costmap_map_server.launch.py'
+        os.getenv('TEST_LAUNCH_DIR', ''), 'costmap_map_server.launch.py'
     )
     testExecutable = os.getenv('TEST_EXECUTABLE')
 
diff --git a/nav2_costmap_2d/test/test_launch_files/costmap_map_server.launch.py b/nav2_costmap_2d/test/test_launch_files/costmap_map_server.launch.py
index 622d55e0745..b3ff9b09beb 100644
--- a/nav2_costmap_2d/test/test_launch_files/costmap_map_server.launch.py
+++ b/nav2_costmap_2d/test/test_launch_files/costmap_map_server.launch.py
@@ -20,7 +20,7 @@
 import launch_ros.actions
 
 
-def generate_launch_description():
+def generate_launch_description() -> LaunchDescription:
     mapFile = os.getenv('TEST_MAP')
     return LaunchDescription(
         [
diff --git a/tools/pyproject.toml b/tools/pyproject.toml
index c1ff5ba55a7..08693d6a353 100644
--- a/tools/pyproject.toml
+++ b/tools/pyproject.toml
@@ -24,6 +24,7 @@ module = [
     "launch.*",
     "ament_index_python.*",
     "nav2_common.*",
+    "launch_testing.*",
 ]
 
 ignore_missing_imports = true