diff --git a/model_server/base/roiset.py b/model_server/base/roiset.py
index 2f20ba9ac68af7cc86d3d513a863fe93f52a9393..e5ec6708425c76ff00856d2221ed2087e9bf2e41 100644
--- a/model_server/base/roiset.py
+++ b/model_server/base/roiset.py
@@ -34,6 +34,7 @@ class PatchParams(BaseModel):
 
 class AnnotatedZStackParams(BaseModel):
     draw_label: bool = False
+    channel: int = None
 
 
 class RoiFilterRange(BaseModel):