diff --git a/pyproject.toml b/pyproject.toml
index 8862d73f..a293763a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "python-engineio"
-version = "4.9.0"
+version = "4.9.1.dev0"
 authors = [{name = "Miguel Grinberg", email = "miguel.grinberg@gmail.com"}]
 description = "Engine.IO server and client for Python"
 classifiers = [