diff --git a/backend/open_webui/routers/audio.py b/backend/open_webui/routers/audio.py
index 9d8938b41..b1886b213 100644
--- a/backend/open_webui/routers/audio.py
+++ b/backend/open_webui/routers/audio.py
@@ -660,7 +660,7 @@ def transcription_handler(request, file_path, metadata, user=None):
         data = {'text': transcript.strip()}
 
         # save the transcript to a json file
-        transcript_file = f'{file_dir}/{id}.json'
+        transcript_file = os.path.join(file_dir, f'{id}.json')
         with open(transcript_file, 'w') as f:
             json.dump(data, f)
 
@@ -698,7 +698,7 @@ def transcription_handler(request, file_path, metadata, user=None):
             data = r.json()
 
             # save the transcript to a json file
-            transcript_file = f'{file_dir}/{id}.json'
+            transcript_file = os.path.join(file_dir, f'{id}.json')
             with open(transcript_file, 'w') as f:
                 json.dump(data, f)
 
@@ -767,7 +767,7 @@ def transcription_handler(request, file_path, metadata, user=None):
             data = {'text': transcript.strip()}
 
             # Save transcript
-            transcript_file = f'{file_dir}/{id}.json'
+            transcript_file = os.path.join(file_dir, f'{id}.json')
             with open(transcript_file, 'w') as f:
                 json.dump(data, f)
 
@@ -874,7 +874,7 @@ def transcription_handler(request, file_path, metadata, user=None):
             data = {'text': transcript}
 
             # Save transcript to json file (consistent with other providers)
-            transcript_file = f'{file_dir}/{id}.json'
+            transcript_file = os.path.join(file_dir, f'{id}.json')
             with open(transcript_file, 'w') as f:
                 json.dump(data, f)
 
@@ -1059,7 +1059,7 @@ def transcription_handler(request, file_path, metadata, user=None):
                 data = {'text': transcript}
 
             # Save transcript to json file (consistent with other providers)
-            transcript_file = f'{file_dir}/{id}.json'
+            transcript_file = os.path.join(file_dir, f'{id}.json')
             with open(transcript_file, 'w') as f:
                 json.dump(data, f)
 
@@ -1237,9 +1237,9 @@ def transcription(
         filename = f'{id}.{ext}'
         contents = file.file.read()
 
-        file_dir = f'{CACHE_DIR}/audio/transcriptions'
+        file_dir = os.path.join(CACHE_DIR, 'audio', 'transcriptions')
         os.makedirs(file_dir, exist_ok=True)
-        file_path = f'{file_dir}/{filename}'
+        file_path = os.path.join(file_dir, filename)
 
         # Defense-in-depth: ensure resolved path stays within intended directory
         if not os.path.realpath(file_path).startswith(os.path.realpath(file_dir)):
diff --git a/backend/open_webui/routers/ollama.py b/backend/open_webui/routers/ollama.py
index 7d5a316fb..5cf87854a 100644
--- a/backend/open_webui/routers/ollama.py
+++ b/backend/open_webui/routers/ollama.py
@@ -1585,7 +1585,7 @@ async def download_model(
     file_name = parse_huggingface_url(form_data.url)
 
     if file_name:
-        file_path = f'{UPLOAD_DIR}/{file_name}'
+        file_path = os.path.join(UPLOAD_DIR, file_name)
 
         return StreamingResponse(
             download_file_stream(url, form_data.url, file_path, file_name),
diff --git a/backend/open_webui/storage/provider.py b/backend/open_webui/storage/provider.py
index 3c2946234..0886c851f 100644
--- a/backend/open_webui/storage/provider.py
+++ b/backend/open_webui/storage/provider.py
@@ -61,7 +61,7 @@ class LocalStorageProvider(StorageProvider):
         contents = file.read()
         if not contents:
             raise ValueError(ERROR_MESSAGES.EMPTY_CONTENT)
-        file_path = f'{UPLOAD_DIR}/{filename}'
+        file_path = os.path.join(UPLOAD_DIR, filename)
         with open(file_path, 'wb') as f:
             f.write(contents)
         return contents, file_path
@@ -74,8 +74,8 @@ class LocalStorageProvider(StorageProvider):
     @staticmethod
     def delete_file(file_path: str) -> None:
         """Handles deletion of the file from local storage."""
-        filename = file_path.split('/')[-1]
-        file_path = f'{UPLOAD_DIR}/{filename}'
+        filename = os.path.basename(file_path)
+        file_path = os.path.join(UPLOAD_DIR, filename)
         if os.path.isfile(file_path):
             os.remove(file_path)
         else:
@@ -202,7 +202,7 @@ class S3StorageProvider(StorageProvider):
         return '/'.join(full_file_path.split('//')[1].split('/')[1:])
 
     def _get_local_file_path(self, s3_key: str) -> str:
-        return f'{UPLOAD_DIR}/{s3_key.split("/")[-1]}'
+        return os.path.join(UPLOAD_DIR, s3_key.split('/')[-1])
 
 
 class GCSStorageProvider(StorageProvider):
@@ -234,7 +234,7 @@ class GCSStorageProvider(StorageProvider):
         """Handles downloading of the file from GCS storage."""
         try:
             filename = file_path.removeprefix('gs://').split('/')[1]
-            local_file_path = f'{UPLOAD_DIR}/{filename}'
+            local_file_path = os.path.join(UPLOAD_DIR, filename)
             blob = self.bucket.get_blob(filename)
             blob.download_to_filename(local_file_path)
 
@@ -298,7 +298,7 @@ class AzureStorageProvider(StorageProvider):
         """Handles downloading of the file from Azure Blob Storage."""
         try:
             filename = file_path.split('/')[-1]
-            local_file_path = f'{UPLOAD_DIR}/{filename}'
+            local_file_path = os.path.join(UPLOAD_DIR, filename)
             blob_client = self.container_client.get_blob_client(filename)
             with open(local_file_path, 'wb') as download_file:
                 download_file.write(blob_client.download_blob().readall())