diff --git a/rustuna_pyo3/pyproject.toml b/rustuna_pyo3/pyproject.toml
index 2a168d7..b4a87ff 100644
--- a/rustuna_pyo3/pyproject.toml
+++ b/rustuna_pyo3/pyproject.toml
@@ -11,7 +11,7 @@ classifiers = [
     "Programming Language :: Rust",
     "Programming Language :: Python :: Implementation :: CPython",
 ]
-version = "0.2.0.dev"
+version = "0.1.1"
 
 [project.urls]
 homepage = "https://optuna.org/"