diff --git a/pyproject.toml b/pyproject.toml
index d92d2e6d..407c0624 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "pyleoclim"
-version = "1.3.0"
+version = "1.3.1b"
 description = "Python Package for the Analysis of Paleoclimate Data"
 readme = "README.md"
 license = { text = "GPL-3.0" }