diff --git a/src/interfaces/source.ts b/src/interfaces/source.ts
index 838654f..48b3401 100644
--- a/src/interfaces/source.ts
+++ b/src/interfaces/source.ts
@@ -56,6 +56,7 @@ export interface Site {
   require_application: boolean;
   application_question?: string;
   private_instance: boolean;
+  default_theme: string;
 }
 
 export interface PrivateMessage {