diff --git a/doc/changelog.md b/doc/changelog.md
index 25cf858f..70523225 100644
--- a/doc/changelog.md
+++ b/doc/changelog.md
@@ -2,6 +2,10 @@
 
 # Change Log
 
+## Sep-19-2024: Version 3.5.1
+
+- A small fix.
+
 ## Sep-13-2024: Version 3.5
 
 - Maintenance release.
diff --git a/doc/conf.py b/doc/conf.py
index cb1804de..a4f00a21 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -60,7 +60,7 @@
 # The short X.Y version.
 version = "3.5"
 # The full version, including alpha/beta/rc tags.
-release = "3.5.0"
+release = "3.5.1"
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
diff --git a/doc/pypolymlp.md b/doc/pypolymlp.md
index bd15f858..aca7c093 100644
--- a/doc/pypolymlp.md
+++ b/doc/pypolymlp.md
@@ -2,6 +2,8 @@
 
 # Force constants calculation using pypolymlp (machine learning potential)
 
+**This is an experimental feature.**
+
 With the `--pypolymlp` option, phono3py can interface with the polynomial
 machine learning potential (MLP) code,
 [pypolymlp](https://github.com/sekocha/pypolymlp), to perform training and
diff --git a/phono3py/version.py b/phono3py/version.py
index d6368a53..b8845155 100644
--- a/phono3py/version.py
+++ b/phono3py/version.py
@@ -34,4 +34,4 @@
 # ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 # POSSIBILITY OF SUCH DAMAGE.
 
-__version__ = "3.5.0"
+__version__ = "3.5.1"