diff --git a/wfobj.py b/wfobj.py
index bc84c06..b2154fb 100755
--- a/wfobj.py
+++ b/wfobj.py
@@ -130,7 +130,7 @@ class WFObj(object):
             if parts[0] == 'newmtl':
                 if len(parts[1:]) < 1:
                     raise ValueError('newmtl directive requires argument on line %d' % lineno)
-                material = Material()
+                material = self.Material()
                 material_name = parts[1]
                 self.materials[material_name] = material
             else: