diff --git a/pisi/metadata.py b/pisi/metadata.py
index 30935855..f1812e06 100644
--- a/pisi/metadata.py
+++ b/pisi/metadata.py
@@ -40,8 +40,7 @@ class Package(specfile.Package):
     __metaclass__ = autoxml.autoxml
     
     # if this is working autoxml r0Xx0rz
-    t_PartOf = [autoxml.String, autoxml.mandatory]
-    
+    t_PartOf = [autoxml.String, autoxml.optional]
     t_Build = [ autoxml.Integer, autoxml.optional]
     t_Distribution = [ autoxml.String, autoxml.mandatory]
     t_DistributionRelease = [ autoxml.String, autoxml.mandatory]