diff --git a/pyproject.toml b/pyproject.toml
index fdcddf4..0e49fc9 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -38,7 +38,7 @@ Repository = "https://github.com/pyiron/atomistics"
 
 [project.optional-dependencies]
 phonopy = [
-    "phonopy==2.26.6",
+    "phonopy==2.28.0",
     "seekpath==2.1.0",
     "structuretoolkit==0.0.28",
 ]