diff --git a/package.json b/package.json
index 1b3dbce..2d2c783 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@ckeditor/ckeditor5-undo",
-  "version": "0.9.0",
+  "version": "1.0.0-alpha.1",
   "description": "Undo manager for CKEditor 5.",
   "keywords": [
     "ckeditor5",