diff --git a/pyproject.toml b/pyproject.toml
index fd7c070..1959839 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -24,6 +24,7 @@ dependencies = [
     # to devdeps in tox.ini
     "jdaviz>=3.10.2,<3.11",
     "lightkurve>=2.4.1",
+    "numpy<2",
 ]
 dynamic = [
     "version",