diff --git a/atomrdf/workflow/pyiron/pyiron.py b/atomrdf/workflow/pyiron/pyiron.py
index a8ff767..99d0713 100644
--- a/atomrdf/workflow/pyiron/pyiron.py
+++ b/atomrdf/workflow/pyiron/pyiron.py
@@ -68,7 +68,7 @@ def bulk(
             repetitions=None,
             crystalstructure=None,
             a=None,
-            covera=None,
+            covera=1.633,
             cubic=True,
             graph=None,
             label=None,