diff --git a/Cargo.toml b/Cargo.toml
index 0febc155..8533c21a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "tskit"
-version = "0.15.0-alpha.3"
+version = "0.15.0-alpha.4"
 authors = ["tskit developers <admin@tskit.dev>"]
 build = "build.rs"
 edition = "2021"