diff --git a/gitlab/v4/objects/appearance.py b/gitlab/v4/objects/appearance.py
index 88ab6215d..f811d2053 100644
--- a/gitlab/v4/objects/appearance.py
+++ b/gitlab/v4/objects/appearance.py
@@ -38,7 +38,7 @@ class ApplicationAppearanceManager(GetWithoutIdMixin, UpdateMixin, RESTManager):
     def update(
         self,
         id: Optional[Union[str, int]] = None,
-        new_data: Dict[str, Any] = None,
+        new_data: Optional[Dict[str, Any]] = None,
         **kwargs: Any
     ) -> Dict[str, Any]:
         """Update an object on the server.
diff --git a/gitlab/v4/objects/repositories.py b/gitlab/v4/objects/repositories.py
index b8dbdd8af..b340e80fb 100644
--- a/gitlab/v4/objects/repositories.py
+++ b/gitlab/v4/objects/repositories.py
@@ -196,7 +196,7 @@ def repository_contributors(
     @exc.on_http_error(exc.GitlabListError)
     def repository_archive(
         self,
-        sha: str = None,
+        sha: Optional[str] = None,
         streamed: bool = False,
         action: Optional[Callable[..., Any]] = None,
         chunk_size: int = 1024,
diff --git a/gitlab/v4/objects/settings.py b/gitlab/v4/objects/settings.py
index 16b1041c5..cc6b1c0b6 100644
--- a/gitlab/v4/objects/settings.py
+++ b/gitlab/v4/objects/settings.py
@@ -93,7 +93,7 @@ class ApplicationSettingsManager(GetWithoutIdMixin, UpdateMixin, RESTManager):
     def update(
         self,
         id: Optional[Union[str, int]] = None,
-        new_data: Dict[str, Any] = None,
+        new_data: Optional[Dict[str, Any]] = None,
         **kwargs: Any
     ) -> Dict[str, Any]:
         """Update an object on the server.
diff --git a/pyproject.toml b/pyproject.toml
index 544543bc8..a8b02200f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -13,6 +13,7 @@ disallow_incomplete_defs = true
 disallow_subclassing_any = true
 disallow_untyped_decorators = true
 disallow_untyped_defs = true
+no_implicit_optional = true
 no_implicit_reexport = true
 strict_equality = true
 warn_redundant_casts = true
@@ -23,7 +24,6 @@ warn_unused_ignores = true
 # The following need to have changes made to be able to enable them:
 # disallow_any_generics = true
 # disallow_untyped_calls = true
-# no_implicit_optional = true
 
 [[tool.mypy.overrides]] # Overrides for currently untyped modules
 module = [