diff --git a/pyproject.toml b/pyproject.toml
index abb8ef1a4..1c59b53b5 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -12,7 +12,7 @@ dependencies = [
     'pandas',
     'numba',
     'numba_celltree',
-    'numpy',
+    'numpy<2.0.0',
     'pooch',
     'scipy',
     'xarray',