diff --git a/pyproject.toml b/pyproject.toml
index 1bae035af..7f5f71663 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -34,7 +34,7 @@ classifiers = [
 dependencies = [
     "h5py>=2.10",
     "hdmf>=3.12.2",
-    "numpy>=1.18", # match the version used in hdmf
+    "numpy>=1.18, <2.0", # pin below 2.0 until HDMF supports numpy 2.0
     "pandas>=1.1.5",
     "python-dateutil>=2.7.3",
 ]