diff --git a/setup.cfg b/setup.cfg
index 08430b80f..038ed0e22 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -22,7 +22,7 @@ python_requires = >=3.8, <3.13
 install_requires =
     attrs >= 20.3.0 
     black
-    numpy
+    numpy < 2.0
     scipy
     tskit >= 0.5.6
     demes ~= 0.2.2