diff --git a/doc/changelog.md b/doc/changelog.md
index 0957959b..ffb7bb19 100644
--- a/doc/changelog.md
+++ b/doc/changelog.md
@@ -2,6 +2,11 @@
 
 # Change Log
 
+## Dec-4-2023: Version 2.8.0
+
+- Maintenance release
+- Fix unit conversion for non-VASP calculators
+
 ## Jul-3-2023: Version 2.7.0
 
 - Drop python 3.7 support
@@ -47,7 +52,7 @@
 
 - Maintenance release to follow the change of phonopy at v2.12.1.
 - Installation using `setup.py` now requires creating `site.cfg` file. See
-  https://phonopy.github.io/phono3py/install.html and
+  <https://phonopy.github.io/phono3py/install.html> and
   [PR #59](https://github.com/phonopy/phono3py/pull/59).
 - Dorp python 3.6 support, and dependencies of numpy and matplotlib versions are
   updated:
diff --git a/doc/conf.py b/doc/conf.py
index b200c680..1d39ae6c 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -57,7 +57,7 @@
 # built documents.
 #
 # The short X.Y version.
-version = "2.7"
+version = "2.8"
 # The full version, including alpha/beta/rc tags.
 release = "2.7.0"
 
diff --git a/phono3py/version.py b/phono3py/version.py
index 7723a618..d34b5e97 100644
--- a/phono3py/version.py
+++ b/phono3py/version.py
@@ -33,4 +33,4 @@
 # ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 # POSSIBILITY OF SUCH DAMAGE.
 
-__version__ = "2.7.0"
+__version__ = "2.8.0"
diff --git a/requirements.txt b/requirements.txt
index e3dc459b..4e13b8dc 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,4 +2,4 @@ numpy >= 1.17.0
 PyYAML >= 5.3
 matplotlib >= 2.2.2
 h5py >= 3.0
-phonopy >=2.20,<2.21
+phonopy >=2.21,<2.22
diff --git a/setup.py b/setup.py
index 8f70a1f0..f1cd0468 100644
--- a/setup.py
+++ b/setup.py
@@ -319,7 +319,7 @@ def main(build_dir):
             "matplotlib>=2.2.2",
             "h5py>=3.0",
             "spglib>=2.0",
-            "phonopy>=2.20,<2.21",
+            "phonopy>=2.21,<2.22",
         ],
         provides=["phono3py"],
         scripts=scripts_phono3py,