diff --git a/pyproject.toml b/pyproject.toml
index d8ca75b..cf49fa3 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -84,8 +84,8 @@ dev = [
     "msprime>=1.2.0",
     "matplotlib>=3.0",
     "pandas>=2.0",
-    "jupyter-book>=1.0",
+    "jupyter-book>=1.0,<2",
     "setuptools-scm>=8.0",
     "sphinx-argparse>=0.5",
     "sphinx-issues>=5.0",
-]
\ No newline at end of file
+]