diff --git a/setup.py b/setup.py
index 4363f3044b174d4bf6f50e728c734c49181a07ad..41772cb7994d391e5e6088d1656f364e4ebc156f 100644
--- a/setup.py
+++ b/setup.py
@@ -38,6 +38,7 @@ setup(
         "pytools>=2021.1",
         "pyrsistent",
         "immutables",
+        "attrs",
         ],
     package_data={"pytato": ["py.typed"]},
     author="Andreas Kloeckner, Matt Wala, Xiaoyu Wei",