diff --git a/pyproject.toml b/pyproject.toml
index 9948b6cf..a0673443 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -23,6 +23,7 @@ requires-python = ">=3.9"
 dependencies = [
     "aiostream",
     "array-api-compat",
+    "cloudpickle",
     "donfig",
     "fsspec",
     "mypy_extensions", # for rechunker