diff --git a/src/ert/analysis/_es_update.py b/src/ert/analysis/_es_update.py
index 2a2468d49d2..05d335e3b4a 100644
--- a/src/ert/analysis/_es_update.py
+++ b/src/ert/analysis/_es_update.py
@@ -901,7 +901,7 @@ def iterative_smoother_update(
         ens_mask=ens_mask,
         source_fs=prior_storage,
         target_fs=posterior_storage,
-        iterative_ensemble_smoother=sies_smoother,
+        sies_smoother=sies_smoother,
         progress_callback=progress_callback,
         misfit_preprocessor=update_settings.misfit_preprocess,
         sies_step_length=sies_step_length,