diff --git a/setup.cfg b/setup.cfg
index 652b928..b8b9d28 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -22,6 +22,7 @@ python_requires = >= 3.10
 install_requires =
     click
     tqdm
+    numpy
     openpathsampling >= 1.6
 packages = find: