diff --git a/setup.cfg b/setup.cfg
index 0df3a1d..1a24d12 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -27,7 +27,8 @@ install_requires =
     numpy>=1.8.0,<2.0; python_version == "3.9" and extra == 'stan'
     numpy>=1.8.0; python_version != "3.9" or extra != 'stan'
     pandas
-    scipy
+    scipy<1.13; python_version == "3.9" and extra == 'stan'
+    scipy; python_version != "3.9" or extra != 'stan'
     sympy
     wrapt
 packages = find: