diff --git a/.readthedocs.yml b/.readthedocs.yml
index 722c2ce..ff6c14c 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -11,6 +11,7 @@ python:
       path: .
       extra_requirements:
         - docs
+        - pydantic
 
 mkdocs:
   configuration: mkdocs.yml
diff --git a/pyproject.toml b/pyproject.toml
index d20c035..42d0ea3 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -16,6 +16,7 @@ docs = [
     "rich",
     "zarr<3",
 ]
+pydantic = ["pydantic"]
 
 [tool.hatch.version]
 source = "vcs"