diff --git a/cal_tools/cal_tools/agipdlib.py b/cal_tools/cal_tools/agipdlib.py
index 558ec084bdc7f843f6f653a7f6b44cb4a88afc90..1ac77d9b8d989e9be1a8a8659362dcc68960aaff 100644
--- a/cal_tools/cal_tools/agipdlib.py
+++ b/cal_tools/cal_tools/agipdlib.py
@@ -1655,8 +1655,8 @@ class AgipdCorrections:
         for cname, mdata in const_yaml[dname].items():
             when[cname] = mdata["creation-time"]
             if when[cname]:
-                cf = h5py.File(mdata["file-path"])
-                cons_data[cname] = np.copy(cf[f"{dname}/{cname}/0/data"])
+                with h5py.File(mdata["file-path"], "r") as cf:
+                    cons_data[cname] = np.copy(cf[f"{dname}/{cname}/0/data"])
             else:
                 # Create empty constant using the list elements
                 cons_data[cname] = \