diff --git a/tests/test_build_images.py b/tests/test_build_images.py
index debf669..d45086b 100644
--- a/tests/test_build_images.py
+++ b/tests/test_build_images.py
@@ -4,20 +4,20 @@ from runboat.build_images import get_build_image, get_main_branch, is_branch_sup
 from runboat.exceptions import BranchNotSupported
 
 
-def test_get_main_branch():
+def test_get_main_branch() -> None:
     assert get_main_branch("15.0") == "15.0"
     assert get_main_branch("15.0-ocabot-merge") == "15.0"
     with pytest.raises(BranchNotSupported):
         get_main_branch("8.0")
 
 
-def test_is_branch_supported():
+def test_is_branch_supported() -> None:
     assert is_branch_supported("15.0")
     assert is_branch_supported("15.0-ocabot-merge")
     assert not is_branch_supported("8.0")
 
 
-def test_get_build_image():
+def test_get_build_image() -> None:
     assert get_build_image("15.0") == "ghcr.io/oca/oca-ci/py3.8-odoo15.0:latest"
     assert get_build_image("15.0-zzz") == "ghcr.io/oca/oca-ci/py3.8-odoo15.0:latest"
     with pytest.raises(BranchNotSupported):
diff --git a/tests/test_db.py b/tests/test_db.py
index 941e82f..4d3cba7 100644
--- a/tests/test_db.py
+++ b/tests/test_db.py
@@ -29,14 +29,14 @@ def _make_build(
     )
 
 
-def test_add():
+def test_add() -> None:
     db = BuildsDb()
     assert db.add(_make_build())  # new
     assert not db.add(_make_build())  # no change
     assert db.add(_make_build(status=BuildStatus.failed))
 
 
-def test_remove():
+def test_remove() -> None:
     db = BuildsDb()
     assert not db.remove("not-a-build")
     build = _make_build()
@@ -44,7 +44,7 @@ def test_remove():
     assert db.remove(build.name)
 
 
-def test_get_for_commit():
+def test_get_for_commit() -> None:
     db = BuildsDb()
     build = _make_build()
     db.add(build)
@@ -62,7 +62,7 @@ def test_get_for_commit():
     )
 
 
-def test_search():
+def test_search() -> None:
     db = BuildsDb()
     db.add(build1 := _make_build(name="b1", repo="oca/repo1"))
     db.add(_make_build(name="b2", repo="oca/repo2"))
@@ -70,7 +70,7 @@ def test_search():
     assert db.search("oca/repo1") == [build1]
 
 
-def test_count_by_status():
+def test_count_by_status() -> None:
     db = BuildsDb()
     db.add(_make_build(name="b1", status=BuildStatus.started))
     db.add(_make_build(name="b2", status=BuildStatus.stopped))
@@ -79,7 +79,7 @@ def test_count_by_status():
     assert db.count_by_status(BuildStatus.failed) == 0
 
 
-def test_count_by_init_status():
+def test_count_by_init_status() -> None:
     db = BuildsDb()
     db.add(_make_build(name="b1", init_status=BuildInitStatus.started))
     db.add(_make_build(name="b2", init_status=BuildInitStatus.todo))
@@ -88,7 +88,7 @@ def test_count_by_init_status():
     assert db.count_by_init_status(BuildInitStatus.failed) == 0
 
 
-def test_count_all():
+def test_count_all() -> None:
     db = BuildsDb()
     assert db.count_all() == 0
     db.add(_make_build(name="b1"))
diff --git a/tests/test_k8s.py b/tests/test_k8s.py
index 68be498..74af7d3 100644
--- a/tests/test_k8s.py
+++ b/tests/test_k8s.py
@@ -10,5 +10,5 @@ from runboat.k8s import _split_image_name_tag
         ("postgres:12", ("postgres", "12")),
     ],
 )
-def test_split_image_name_tag(image, expected):
+def test_split_image_name_tag(image: str, expected: tuple[str, str]) -> None:
     assert _split_image_name_tag(image) == expected
diff --git a/tests/test_render_kubefiles.py b/tests/test_render_kubefiles.py
index a150afb..e703e8c 100644
--- a/tests/test_render_kubefiles.py
+++ b/tests/test_render_kubefiles.py
@@ -65,7 +65,7 @@ patches:
 """
 
 
-def test_render_kubefiles():
+def test_render_kubefiles() -> None:
     deployment_vars = make_deployment_vars(
         mode=DeploymentMode.deployment,
         build_name="build-name",