diff --git a/src/IndexedDB/Browser.IndexedDB.fs b/src/IndexedDB/Browser.IndexedDB.fs
index 8ea0a20..2f17a0d 100644
--- a/src/IndexedDB/Browser.IndexedDB.fs
+++ b/src/IndexedDB/Browser.IndexedDB.fs
@@ -141,7 +141,7 @@ type [<AllowNullLiteral; Global>] IDBObjectStore =
     abstract count: ?query: IDBKeyRange -> IDBRequest
     abstract createIndex: indexName: string * keyPath: string * ?options: IDBCreateIndexOptions -> IDBRequest
     abstract delete: key: obj -> IDBRequest
-    abstract deleteIndex: unit -> IDBRequest
+    abstract deleteIndex: string -> IDBRequest
     abstract get: key: obj -> IDBRequest
     abstract getKey: key: obj -> IDBRequest
     abstract getAll: ?query: IDBKeyRange * ?count: int -> IDBRequest