diff --git a/DDCore/python/dd4hep.py b/DDCore/python/dd4hep.py
index e8fd67cc7995e6d9632cc2faef464cbd71e45b6d..d2626136a4b45bedb0ef42cc9ba13c076b296bdf 100644
--- a/DDCore/python/dd4hep.py
+++ b/DDCore/python/dd4hep.py
@@ -9,5 +9,4 @@
 #
 #==========================================================================
 from dd4hep_base import *
-self = __import__(__name__)
-import_units(self)
+import_units(__import__(__name__))
diff --git a/DDCore/python/dd4hep_base.py b/DDCore/python/dd4hep_base.py
index 995610fb041748d44b20d8d3659308ef0a89f4a9..5a82370b6b9c51f78f1c4c38d7851303f8399ce2 100644
--- a/DDCore/python/dd4hep_base.py
+++ b/DDCore/python/dd4hep_base.py
@@ -241,7 +241,7 @@ import_geometry()
 #
 try:
   from ROOT import TGeoUnit as TGeoUnits
-  def import_units(ns):
+  def import_units(ns=None):
     def import_unit(ns,nam):
       setattr(ns,nam,getattr(TGeoUnits,nam))
     items = dir(TGeoUnits)