diff --git a/pyproject.toml b/pyproject.toml
index 08665fa1..538ab445 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -117,7 +117,7 @@ dev = [
     "attrs",
     "pandas",
     "stdpopsim",
-    "jupyter-book",
+    "jupyter-book<2",
     "sphinx-issues",
     "sphinx-argparse",
     "sphinxcontrib-bibtex",