diff --git a/covsirphy/__version__.py b/covsirphy/__version__.py
index c7d261d00..911557b86 100644
--- a/covsirphy/__version__.py
+++ b/covsirphy/__version__.py
@@ -1 +1 @@
-__version__ = "3.1.1.dev0"
+__version__ = "3.1.2"
diff --git a/pyproject.toml b/pyproject.toml
index 3c6d885e2..c9c89ca53 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "covsirphy"
-version = "3.1.1"
+version = "3.1.2"
 description = "COVID-19 data analysis with phase-dependent SIR-derived ODE models"
 authors = ["Hirokazu Takaya <lisphilar@outlook.jp>"]
 license = "Apache-2.0"