diff --git a/pyproject.toml b/pyproject.toml
index ba39e09..c895369 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -3,7 +3,7 @@ name = "ndradex"
 version = "0.3.0"
 description = " Multidimensional grid RADEX calculator"
 authors = ["Akio Taniguchi <taniguchi@a.phys.nagoya-u.ac.jp>"]
-keywords = ["astronomy", "radio-astronomy", "radex"]
+keywords = ["astronomy", "radio-astronomy", "radex", "xarray"]
 license = "MIT"
 homepage = "https://github.com/astropenguin/ndradex/"
 documentation = "https://astropenguin.github.io/ndradex/"