diff --git a/synapse/rest/client/v1/push_rule.py b/synapse/rest/client/v1/push_rule.py
index 3db38a949a..822c978e85 100644
--- a/synapse/rest/client/v1/push_rule.py
+++ b/synapse/rest/client/v1/push_rule.py
@@ -387,7 +387,7 @@ def _priority_class_from_spec(spec):
 def _priority_class_to_template_name(pc):
     if pc > PRIORITY_CLASS_MAP['override']:
         # per-device
-        prio_class_index = pc - len(PushRuleRestServlet.PRIORITY_CLASS_MAP)
+        prio_class_index = pc - len(PRIORITY_CLASS_MAP)
         return PRIORITY_CLASS_INVERSE_MAP[prio_class_index]
     else:
         return PRIORITY_CLASS_INVERSE_MAP[pc]