diff --git a/tools/python/xen/xend/XendDomainInfo.py b/tools/python/xen/xend/XendDomainInfo.py
index 4e01041342..029021f13e 100644
--- a/tools/python/xen/xend/XendDomainInfo.py
+++ b/tools/python/xen/xend/XendDomainInfo.py
@@ -138,7 +138,7 @@ def dom_get(dom):
     if domlist and dom == domlist[0]['dom']:
         return domlist[0]
     return None
-    
+
 class XendDomainInfo:
     """Virtual machine object."""
 
@@ -754,7 +754,7 @@ class XendDomainInfo:
         @param dev_config: device configuration
         """
         dev_type = sxp.name(dev_config)
-        dev = self.createDevice(self, dev_config, change=True)
+        dev = self.createDevice(dev_type, dev_config, change=True)
         self.config.append(['device', dev.getConfig()])
         return dev.sxpr()
 
diff --git a/tools/python/xen/xend/server/controller.py b/tools/python/xen/xend/server/controller.py
index f399503d7f..a1446c3093 100755
--- a/tools/python/xen/xend/server/controller.py
+++ b/tools/python/xen/xend/server/controller.py
@@ -142,7 +142,7 @@ class DevControllerTable:
     def createDevController(self, type, vm, recreate=False):
         cls = self.getDevControllerClass(type)
         if not cls:
-            raise XendError("unknown device type: " + type)
+            raise XendError("unknown device type: " + str(type))
         return cls.createDevController(vm, recreate=recreate)
 
 def getDevControllerTable():
@@ -283,6 +283,8 @@ class DevController:
         dev.attach(recreate=recreate, change=change)
         dev.exportToDB()
 
+        return dev
+
     def configureDevice(self, id, config, change=False):
         """Reconfigure an existing device.
         May be defined in subclass."""
@@ -325,7 +327,7 @@ class DevController:
     def getDevice(self, id, error=False):
         dev = self.devices.get(id)
         if error and not dev:
-            raise XendError("invalid device id: " + id)
+            raise XendError("invalid device id: " + str(id))
         return dev
 
     def getDeviceIds(self):