diff --git a/index.d.ts b/index.d.ts
index 38fde09..ba4af3a 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -419,7 +419,7 @@ declare module "flexsearch" {
         db?: StorageInterface;
     };
 
-    export type TagOptions<D = DocumentData> = DefaultFieldOptions<D>;
+    export type TagOptions<D = DocumentData> = DefaultFieldOptions<D> | DefaultCustomFieldOptions<D>;
 
     export type StoreOptions<D = DocumentData> = DefaultFieldOptions<D> | DefaultCustomFieldOptions<D>;