diff --git a/pyproject.toml b/pyproject.toml
index 951ce21..5a3a014 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -31,7 +31,7 @@ dependencies = [
   "importlib-metadata~=6.0;python_version<'3.10'",
   "importlib-resources~=5.0;python_version<'3.9'",
   "nbclient~=0.5.10",
-  "nbdime",
+  "nbdime<4",
   "nbformat",
   "jsonschema",
 ]