diff --git a/builtin.aqua b/builtin.aqua
index 9749e21..dd250f6 100644
--- a/builtin.aqua
+++ b/builtin.aqua
@@ -14,6 +14,8 @@ alias Path : string
 data Service:
     id: string
     blueprint_id: string
+    -- `spell` or `service`
+    service_type: string
     owner_id: string
     aliases: []string
     worker_id: string