diff --git a/pyproject.toml b/pyproject.toml
index e938819e6f..49cd3875d0 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -7,7 +7,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "awkward"
-version = "2.5.0"
+version = "2.5.1rc1"
 description = "Manipulate JSON-like data with NumPy-like idioms."
 license = { text = "BSD-3-Clause" }
 requires-python = ">=3.8"