diff --git a/fastapi/dependencies/utils.py b/fastapi/dependencies/utils.py
index 081b63a8b..31f3665da 100644
--- a/fastapi/dependencies/utils.py
+++ b/fastapi/dependencies/utils.py
@@ -966,7 +966,7 @@ def get_body_field(
     first_param = flat_dependant.body_params[0]
     if not embed_body_fields:
         return first_param
-    model_name = "Body_" + name
+    model_name = f"Body_{name}"
     BodyModel = create_body_model(
         fields=flat_dependant.body_params, model_name=model_name
     )
diff --git a/fastapi/utils.py b/fastapi/utils.py
index 4c7350fea..161e107cd 100644
--- a/fastapi/utils.py
+++ b/fastapi/utils.py
@@ -71,7 +71,6 @@ def create_model_field(
     alias: Optional[str] = None,
     mode: Literal["validation", "serialization"] = "validation",
 ) -> ModelField:
-    class_validators = class_validators or {}
     if PYDANTIC_V2:
         field_info = field_info or FieldInfo(
             annotation=type_, default=default, alias=alias
@@ -85,7 +84,7 @@ def create_model_field(
         kwargs.update(
             {
                 "type_": type_,
-                "class_validators": class_validators,
+                "class_validators": class_validators or {},
                 "default": default,
                 "required": required,
                 "model_config": model_config,