diff --git a/pcmdi_metrics/io/xcdat_openxml.py b/pcmdi_metrics/io/xcdat_openxml.py
index 5c3b2208c..423cf3dd2 100644
--- a/pcmdi_metrics/io/xcdat_openxml.py
+++ b/pcmdi_metrics/io/xcdat_openxml.py
@@ -114,7 +114,7 @@ def fix_noncompliant_attr(ds: xr.Dataset) -> xr.Dataset:
 
 
 def _xcdat_openxml(
-    xmlfile: str, data_var: str = None, decode_times: bool = True
+    xmlfile: str, data_var: str = None, decode_times: bool = True, chunks=None
 ) -> xr.Dataset:
     """Open input file (xml generated by cdscan)
 
@@ -142,11 +142,11 @@ def _xcdat_openxml(
 
     if len(ncfile_list) > 1:
         ds = xc.open_mfdataset(
-            ncfile_list, data_var=data_var, decode_times=decode_times
+            ncfile_list, data_var=data_var, decode_times=decode_times, chunks=chunks
         )
     else:
         ds = xc.open_dataset(
-            ncfile_list[0], data_var=data_var, decode_times=decode_times
+            ncfile_list[0], data_var=data_var, decode_times=decode_times, chunks=chunks
         )
 
     return ds