diff --git a/.readthedocs.yaml b/.readthedocs.yaml
index a06d0280a..0bd5eba50 100644
--- a/.readthedocs.yaml
+++ b/.readthedocs.yaml
@@ -25,6 +25,7 @@ formats: all
 python:
   install:
     - requirements: requirements-doc.txt
+    - requirements: requirements-opt.txt
     - requirements: requirements.txt
 
 # Optionally include all submodules
diff --git a/requirements-doc.txt b/requirements-doc.txt
index c37aee646..b1d575fff 100644
--- a/requirements-doc.txt
+++ b/requirements-doc.txt
@@ -13,3 +13,4 @@ lxml  # used by dataframe_image when using the matplotlib backend
 hdf5plugin
 dandi>=0.46.6
 hdmf-zarr
+zarr<2.18.0
\ No newline at end of file