diff --git a/plstackapi/core/models/sliver.py b/plstackapi/core/models/sliver.py
index ba0b2bfe..8f8dedc 100644
--- a/plstackapi/core/models/sliver.py
+++ b/plstackapi/core/models/sliver.py
@@ -25,7 +25,7 @@
     def __unicode__(self):  return u'%s::%s' % (self.slice, self.deploymentNetwork)
 
     def save(self, *args, **kwds):
-        if not self.slice.subnet:
+        if not self.slice.subnet.exists():
             raise exceptions.ValidationError, "Slice %s has no subnet" % self.slice.name
 
         if not self.instance_id: