diff --git a/tailbone/views/master.py b/tailbone/views/master.py
index 304494c3..3ae2be88 100644
--- a/tailbone/views/master.py
+++ b/tailbone/views/master.py
@@ -3883,7 +3883,7 @@ class MasterView(View):
         """
         Iterate over all registered supplements for this master view.
         """
-        supplements = self.request.registry.settings['tailbone_view_supplements']
+        supplements = self.request.registry.settings.get('tailbone_view_supplements', [])
         route_prefix = self.get_route_prefix()
         if supplements and route_prefix in supplements:
             for cls in supplements[route_prefix]: