diff --git a/services/xai_service.py b/services/xai_service.py
index eca4758..fb219d8 100644
--- a/services/xai_service.py
+++ b/services/xai_service.py
@@ -69,8 +69,16 @@ class XAIService:
         url = f"{XAI_FILES_URL}/v1/files"
         headers = {"Authorization": f"Bearer {self.api_key}"}
 
-        form = aiohttp.FormData()
-        form.add_field('file', file_content, filename=filename, content_type=mime_type)
+        # Create multipart form with explicit UTF-8 filename encoding
+        # aiohttp automatically URL-encodes filenames with special chars,
+        # but xAI expects raw UTF-8 in the filename parameter
+        form = aiohttp.FormData(quote_fields=False)
+        form.add_field(
+            'file',
+            file_content,
+            filename=filename,
+            content_type=mime_type
+        )
 
         async with session.post(url, data=form, headers=headers) as response:
             try: