diff --git a/spack-environment/dev/spack.yaml b/spack-environment/dev/spack.yaml
index b9968c773155db166314f79af76256ff9aa4ce81..becad13a9eb28f3f967a997b686ac41320fa1fa3 100644
--- a/spack-environment/dev/spack.yaml
+++ b/spack-environment/dev/spack.yaml
@@ -51,6 +51,7 @@ spack:
     - pythia8@8.306 +fastjet
     - python@3.10.8
     - py-awkward@1.9.0
+    - py-dask@2021.6.2
     - py-boto3@1.18.12
     - py-ipython@8.5.0
     - py-jinja2@3.1.2