diff --git a/csst/msc/calib_pos.py b/csst/msc/calib_pos.py
index 6fdcf21cbf82487127fe9175abae0293870abcd9..f439f09bf529c2e4325f15571a33abee30b7496d 100644
--- a/csst/msc/calib_pos.py
+++ b/csst/msc/calib_pos.py
@@ -80,9 +80,9 @@ class CsstProcMscPositionCalibration(CsstProcessor):
         """
         cat_list = []
         fn_list = []
-        ccd_ids=int(ccd_ids)
         for this_ccd_id in ccd_ids:
             print(type(this_ccd_id))
+            this_ccd_id=int(this_ccd_id)
             sex_cat = self.dm.l1_sci(ccd_id = this_ccd_id, suffix="img", ext="cat")
             fn = self.dm.l1_sci(ccd_id=this_ccd_id, suffix="img", ext="fits")
             cat_list.append(sex_cat)