diff --git a/pyproject.toml b/pyproject.toml
index 506c8c2..cc6b695 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -19,7 +19,7 @@ dependencies = [
     "agjax",
     "ceviche_challenges",
     "fmmax",
-    "jax",
+    "jax <= 0.4.34",
     "jaxlib",
     "numpy",
     "refractiveindex",