diff --git a/app/main.py b/app/main.py
index 532a4bc..7e24788 100644
--- a/app/main.py
+++ b/app/main.py
@@ -1,3 +1,4 @@
+from starlette.datastructures import UploadFile as StarletteUploadFile
 import uvicorn
 from fastapi import FastAPI, File, UploadFile, HTTPException, Form
 from typing import Optional, Union
@@ -7,8 +8,6 @@ from services import ocr_service
 
 app = FastAPI()
 
-from starlette.datastructures import UploadFile as StarletteUploadFile
-
 
 async def decode_image(image: Union[UploadFile, StarletteUploadFile, str, None]) -> bytes:
     if image is None:
@@ -24,7 +23,8 @@ async def decode_image(image: Union[UploadFile, StarletteUploadFile, str, None])
                 image = image.split(',')[1]
             return base64.b64decode(image)
         except:
-            raise HTTPException(status_code=400, detail="Invalid base64 string")
+            raise HTTPException(
+                status_code=400, detail="Invalid base64 string")
     else:
         raise HTTPException(status_code=400, detail="Invalid image input")
 
@@ -38,11 +38,12 @@ async def ocr_endpoint(
         png_fix: bool = Form(False)
 ):
     try:
-        if file.size == 0 and image is None:
+        if file and file.file._file is None and image is None:
             return APIResponse(code=400, message="Either file or image must be provided")
 
         image_bytes = await decode_image(file or image)
-        result = ocr_service.ocr_classification(image_bytes, probability, charsets, png_fix)
+        result = ocr_service.ocr_classification(
+            image_bytes, probability, charsets, png_fix)
         return APIResponse(code=200, message="Success", data=result)
     except Exception as e:
         return APIResponse(code=500, message=str(e))
@@ -57,12 +58,12 @@ async def slide_match_endpoint(
         simple_target: bool = Form(False)
 ):
     try:
-        if (background is None and target is None) or (background_file.size == 0 and target_file.size == 0):
+        if (background is None and background_file and background_file.file._file is None) or (target is None and target_file and target_file.file._file is None):
             return APIResponse(code=400, message="Both target and background must be provided")
-
         target_bytes = await decode_image(target_file or target)
         background_bytes = await decode_image(background_file or background)
-        result = ocr_service.slide_match(target_bytes, background_bytes, simple_target)
+        result = ocr_service.slide_match(
+            target_bytes, background_bytes, simple_target)
         return APIResponse(code=200, message="Success", data=result)
     except Exception as e:
         return APIResponse(code=500, message=str(e))
@@ -74,7 +75,7 @@ async def detection_endpoint(
         image: Optional[str] = Form(None)
 ):
     try:
-        if file.size == 0 and image is None:
+        if file and file.file._file is None and image is None:
             return APIResponse(code=400, message="Either file or image must be provided")
 
         image_bytes = await decode_image(file or image)