diff --git a/docs/environment.yml b/docs/environment.yml
index a2f961554..c6aa7743e 100644
--- a/docs/environment.yml
+++ b/docs/environment.yml
@@ -6,7 +6,7 @@ dependencies:
   - fenics-dolfinx
   - matplotlib==3.7.1
   - pip>=20.1
-  - sphinx<8
+  - sphinx<8 # sphinxcontrib-images is not compatible with sphinx 8
   - folium
   - numpy==1.24
   - tqdm