diff --git a/python/sglang/srt/configs/utils.py b/python/sglang/srt/configs/utils.py
index 8403d95da..16575dfe8 100644
--- a/python/sglang/srt/configs/utils.py
+++ b/python/sglang/srt/configs/utils.py
@@ -15,7 +15,9 @@ def register_image_processor(
     """
     register customized hf image processor while removing hf impl
     """
-    AutoImageProcessor.register(config, None, image_processor, None, exist_ok=True)
+    AutoImageProcessor.register(
+        config, slow_image_processor_class=image_processor, exist_ok=True
+    )
 
 
 def register_processor(config: Type[PretrainedConfig], processor: Type[ProcessorMixin]):