diff --git a/modflow_devtools/dfn.py b/modflow_devtools/dfn.py
index adf8d72..fd414b3 100644
--- a/modflow_devtools/dfn.py
+++ b/modflow_devtools/dfn.py
@@ -434,7 +434,7 @@ def _fields() -> Vars:
         transient_index_vars = flat.getlist("iper")
         for transient_index in transient_index_vars:
             transient_block = transient_index["block"]
-            blocks[transient_block]["transient"] = True
+            blocks[transient_block]["transient_block"] = True
 
         # remove unneeded variable attributes
         def remove_attrs(path, key, value):