diff --git a/homeassistant/components/device_tracker/__init__.py b/homeassistant/components/device_tracker/__init__.py
index 04cc9f7d6d1..c753321790f 100644
--- a/homeassistant/components/device_tracker/__init__.py
+++ b/homeassistant/components/device_tracker/__init__.py
@@ -301,7 +301,7 @@ class DeviceTracker(object):
 
         # During init, we ignore the group
         self.group.async_set_group(
-            self.hass, slugify(GROUP_NAME_ALL_DEVICES), visible=False,
+            self.hass, util.slugify(GROUP_NAME_ALL_DEVICES), visible=False,
             name=GROUP_NAME_ALL_DEVICES, delta=[device.entity_id])
 
         # lookup mac vendor string to be stored in config
diff --git a/homeassistant/components/group.py b/homeassistant/components/group.py
index d20522aa832..a118708b963 100644
--- a/homeassistant/components/group.py
+++ b/homeassistant/components/group.py
@@ -146,7 +146,7 @@ def set_group(hass, object_id, name=None, entity_ids=None, visible=None,
 
 @callback
 def async_set_group(hass, object_id, name=None, entity_ids=None, visible=None,
-                    icon=None, view=None, control=None):
+                    icon=None, view=None, control=None, delta=None):
     """Create a new user group."""
     data = {
         key: value for key, value in [