diff --git a/frozenlist/__init__.py b/frozenlist/__init__.py
index 4022db5..0afde37 100644
--- a/frozenlist/__init__.py
+++ b/frozenlist/__init__.py
@@ -5,7 +5,7 @@
 from functools import total_ordering
 from typing import Any, Type
 
-__version__ = "1.5.0"
+__version__ = "1.5.1.dev0"
 
 __all__ = ("FrozenList", "PyFrozenList")  # type: Tuple[str, ...]