diff --git a/fastapi/dependencies/utils.py b/fastapi/dependencies/utils.py
index ce2c07fad3..d6e1c1cce3 100644
--- a/fastapi/dependencies/utils.py
+++ b/fastapi/dependencies/utils.py
@@ -350,7 +350,7 @@ def add_non_field_param_to_dependency(
 def _is_optional_type(annotation: Any) -> bool:
     """
     Check if a type annotation is Optional (Union with None).
-    
+
     Optional[X] is equivalent to Union[X, None], so we check if:
     1. The origin is Union
     2. NoneType is one of the union args
diff --git a/tests/test_request_params/test_form/test_optional_literal_form.py b/tests/test_request_params/test_form/test_optional_literal_form.py
index ce0ea0c12f..11f9916ab6 100644
--- a/tests/test_request_params/test_form/test_optional_literal_form.py
+++ b/tests/test_request_params/test_form/test_optional_literal_form.py
@@ -1,4 +1,5 @@
 from typing import Annotated, Literal, Optional
+
 from fastapi import FastAPI, Form
 from fastapi.testclient import TestClient
 
@@ -8,9 +9,7 @@ def test_optional_literal_form_none():
     app = FastAPI()
 
     @app.post("/")
-    async def read_main(
-        attribute: Annotated[Optional[Literal["abc", "def"]], Form()]
-    ):
+    async def read_main(attribute: Annotated[Optional[Literal["abc", "def"]], Form()]):
         return {"attribute": attribute}
 
     client = TestClient(app)
@@ -26,9 +25,7 @@ def test_optional_literal_form_valid_values():
     app = FastAPI()
 
     @app.post("/")
-    async def read_main(
-        attribute: Annotated[Optional[Literal["abc", "def"]], Form()]
-    ):
+    async def read_main(attribute: Annotated[Optional[Literal["abc", "def"]], Form()]):
         return {"attribute": attribute}
 
     client = TestClient(app)
@@ -49,9 +46,7 @@ def test_optional_literal_form_invalid_value():
     app = FastAPI()
 
     @app.post("/")
-    async def read_main(
-        attribute: Annotated[Optional[Literal["abc", "def"]], Form()]
-    ):
+    async def read_main(attribute: Annotated[Optional[Literal["abc", "def"]], Form()]):
         return {"attribute": attribute}
 
     client = TestClient(app)
@@ -70,9 +65,7 @@ def test_optional_literal_form_empty_string():
     app = FastAPI()
 
     @app.post("/")
-    async def read_main(
-        attribute: Annotated[Optional[Literal["abc", "def"]], Form()]
-    ):
+    async def read_main(attribute: Annotated[Optional[Literal["abc", "def"]], Form()]):
         return {"attribute": attribute}
 
     client = TestClient(app)