diff --git a/devtools/conda-envs/docs.yml b/devtools/conda-envs/docs.yml
index b0718227..2bf1ff51 100644
--- a/devtools/conda-envs/docs.yml
+++ b/devtools/conda-envs/docs.yml
@@ -3,6 +3,7 @@ channels:
   - conda-forge
 
 dependencies:
+  - python<3.13
   - sphinx>=5.0,<6
   - sphinx_rtd_theme
   - async-lru