diff --git a/devtools/conda-envs/test_env_jax.yaml b/devtools/conda-envs/test_env_jax.yaml
index d466eeae..c2dd795e 100644
--- a/devtools/conda-envs/test_env_jax.yaml
+++ b/devtools/conda-envs/test_env_jax.yaml
@@ -22,4 +22,5 @@ dependencies:
   - xlrd
     # Docs
   - numpydoc
+  - sphinx <7
   - sphinxcontrib-bibtex