diff --git a/pyproject.toml b/pyproject.toml
index a44165931..7f065bad2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -52,6 +52,7 @@ doc = [
   "numpydoc",
   "openneuro-py",
   "pandas",
+  "pathlib",
   "pillow",
   "pydata-sphinx-theme",
   "seaborn",