diff --git a/pyproject.toml b/pyproject.toml
index c0c4319..b6cd5f4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "forge-py"
-version = "0.5.0a1"
+version = "0.4.0rc1"
 description = "forge-py is a footprint generator (FOotpRint GEnerator) from science data netcdf files"
 authors = ["James Wood <James.F.Wood@jpl.nasa.gov>"]
 readme = "README.md"