diff --git a/fastapi_code_generator/parser.py b/fastapi_code_generator/parser.py
index 38f9156..60bc0fb 100644
--- a/fastapi_code_generator/parser.py
+++ b/fastapi_code_generator/parser.py
@@ -330,7 +330,7 @@ def get_argument_list(self, snake_case: bool, path: List[str]) -> List[Argument]
         for argument in arguments:
             if positional_argument and argument.required and argument.default is None:
                 argument.default = UsefulStr('...')
-            positional_argument = argument.required
+            positional_argument = argument.required or argument.default is not None
 
         return arguments
 
diff --git a/tests/data/expected/openapi/default_template/body_and_parameters/main.py b/tests/data/expected/openapi/default_template/body_and_parameters/main.py
index 9789cce..47bd8d9 100644
--- a/tests/data/expected/openapi/default_template/body_and_parameters/main.py
+++ b/tests/data/expected/openapi/default_template/body_and_parameters/main.py
@@ -6,7 +6,7 @@
 
 from typing import List, Optional, Union
 
-from fastapi import FastAPI, Path, Query
+from fastapi import FastAPI, Path, Query, UploadFile
 from starlette.requests import Request
 
 from .models import (
@@ -36,6 +36,11 @@ def post_bar(request: Request) -> None:
     pass
 
 
+@app.post('/convert', response_model=bytes)
+def convert(format: Optional[str] = 'pdf', file: UploadFile = ...) -> bytes:
+    pass
+
+
 @app.get('/foo', response_model=str, tags=['foo'])
 def get_foo(foo: Optional[str] = None) -> str:
     pass
diff --git a/tests/data/openapi/default_template/body_and_parameters.yaml b/tests/data/openapi/default_template/body_and_parameters.yaml
index 340fbf3..a373049 100644
--- a/tests/data/openapi/default_template/body_and_parameters.yaml
+++ b/tests/data/openapi/default_template/body_and_parameters.yaml
@@ -337,6 +337,29 @@ paths:
             schema:
               $ref: '#/components/schemas/Pet'
         required: true
+  /convert:
+    post:
+      operationId: convert
+      parameters:
+        - in: query
+          name: format
+          schema:
+            type: string
+            default: pdf
+      requestBody:
+        required: true
+        content:
+          application/octet-stream:
+            schema:
+              type: string
+              format: binary
+      responses:
+        "200":
+          content:
+            application/octet-stream:
+              schema:
+                type: string
+                format: binary
 components:
   parameters:
     MyParam: