diff --git a/datasette/extras.py b/datasette/extras.py
index fb8c2e0..c9b500d 100644
--- a/datasette/extras.py
+++ b/datasette/extras.py
@@ -96,7 +96,7 @@ class ExtraRegistry:
     def _registry_for_scope(self, scope):
         registry = self._scope_registries.get(scope)
         if registry is None:
-            registry = Registry()
+            registry = Registry(parallel=False)
             for cls in self.classes_for_scope(scope):
                 registry.register(cls().resolve, name=cls.key())
             self._scope_registries[scope] = registry