diff --git a/studio/backend/routes/inference.py b/studio/backend/routes/inference.py
index 13062f8b29..6740abbc58 100644
--- a/studio/backend/routes/inference.py
+++ b/studio/backend/routes/inference.py
@@ -860,6 +860,23 @@ async def openai_chat_completions(
                 detail = "Image provided but current GGUF model does not support vision.",
             )
 
+        # Convert image to PNG for llama-server (stb_image has limited format support)
+        if image_b64:
+            try:
+                import base64 as _b64
+                from io import BytesIO as _BytesIO
+                from PIL import Image as _Image
+
+                raw = _b64.b64decode(image_b64)
+                img = _Image.open(_BytesIO(raw))
+                if img.mode == "RGBA":
+                    img = img.convert("RGB")
+                buf = _BytesIO()
+                img.save(buf, format = "PNG")
+                image_b64 = _b64.b64encode(buf.getvalue()).decode("ascii")
+            except Exception as e:
+                raise HTTPException(status_code = 400, detail = f"Failed to process image: {e}")
+
         # Build message list with system prompt prepended
         gguf_messages = []
         if system_prompt: