diff --git a/maintainer/conda/environment.yml b/maintainer/conda/environment.yml
index 6a5bf0cb7e6..dbb46da2d89 100644
--- a/maintainer/conda/environment.yml
+++ b/maintainer/conda/environment.yml
@@ -14,6 +14,7 @@ dependencies:
   - hypothesis
   - joblib>=0.12
   - mdanalysis-sphinx-theme
+  - sphinx_rtd_theme >=1.2
   - matplotlib>=3.2.2
   - mmtf-python
   - mock