diff --git a/README.md b/README.md
index 16dc8c320ffc06a1c5d7484497a07bab52fd02a0..212dbd37e383eba0ff0d2cbad46f0c5322d72d18 100644
--- a/README.md
+++ b/README.md
@@ -53,7 +53,7 @@ omo = openmf.open_mfdataset_optimized(
 
 outstore=tzis.write_zarr(
     omo.target_fsmap,
-    omo.mf_dset,
+    omo,
     omo.varname,
     verbose=True,
     target_mb=0