diff --git a/.ci_support/environment.yml b/.ci_support/environment.yml
index 9b8910d8a..ec7091991 100644
--- a/.ci_support/environment.yml
+++ b/.ci_support/environment.yml
@@ -7,7 +7,7 @@ dependencies:
 - matplotlib-base =3.8.2
 - nglview =3.0.8
 - numpy =1.26.2
-- phonopy =2.20.0
+- phonopy =2.21.0
 - plotly =5.18.0
 - pymatgen =2023.11.12
 - pyscal =2.10.18
diff --git a/pyproject.toml b/pyproject.toml
index 376cc5b49..4e0bc94d3 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -51,7 +51,7 @@ surface = [
     "pymatgen==2023.11.12",
 ]
 phonopy = [
-    "phonopy==2.20.0",
+    "phonopy==2.21.0",
     "spglib==2.1.0",
 ]
 pyxtal = ["pyxtal==0.6.1"]