diff --git a/qubesadmin/devices.py b/qubesadmin/devices.py
index 4993b01..fc08fd8 100644
--- a/qubesadmin/devices.py
+++ b/qubesadmin/devices.py
@@ -303,7 +303,7 @@ class DeviceManager(dict):
         return self[key]
 
     def __iter__(self):
-        yield from self._get_device_classes()
+        return iter(self._get_device_classes())
 
     def keys(self):
         return self._get_device_classes()