diff --git a/qubes/app.py b/qubes/app.py
index 804545b1..8a785035 100644
--- a/qubes/app.py
+++ b/qubes/app.py
@@ -708,7 +708,9 @@ class Qubes(qubes.PropertyHolder):
 
         pools_xml = lxml.etree.Element('pools')
         for pool in self.pools.values():
-            pools_xml.append(pool.__xml__())
+            xml = pool.__xml__()
+            if xml is not None:
+                pools_xml.append(xml)
 
         element.append(pools_xml)
 
diff --git a/qubes/storage/domain.py b/qubes/storage/domain.py
index b5a275d6..a84be882 100644
--- a/qubes/storage/domain.py
+++ b/qubes/storage/domain.py
@@ -64,6 +64,9 @@ class DomainPool(Pool):
     def clone(self, source, target):
         raise NotImplementedError
 
+    def __xml__(self):
+        return None
+
 
 class DomainVolume(Volume):
     ''' A volume provided by a block device in an domain '''