diff --git a/pyproject.toml b/pyproject.toml
index 4653b435..ac763bb6 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "python-socketio"
-version = "5.12.0"
+version = "5.12.1.dev0"
 authors = [
     { name = "Miguel Grinberg", email = "miguel.grinberg@gmail.com" },
 ]