diff --git a/spack-ext/repos/spack-stack/packages/gmao-swell-env/package.py b/spack-ext/repos/spack-stack/packages/gmao-swell-env/package.py
index 092fe668e..ec30399c4 100644
--- a/spack-ext/repos/spack-stack/packages/gmao-swell-env/package.py
+++ b/spack-ext/repos/spack-stack/packages/gmao-swell-env/package.py
@@ -47,6 +47,8 @@ class GmaoSwellEnv(BundlePackage):
     depends_on("py-setuptools", type="run")
     depends_on("py-pycodestyle", type="run")
     depends_on("py-pyyaml", type="run")
+    depends_on("py-ruamel-yaml", type="run")
+    depends_on("py-ruamel-yaml-clib", type="run")
     # Note that the +delayed option is for compatibility
     # with the py-xnrl package (this restricts py-dask
     # to certain versions, since the newest versions