diff --git a/setup.py b/setup.py
index 198ad016..c55dee9a 100644
--- a/setup.py
+++ b/setup.py
@@ -33,7 +33,7 @@
         history_file.read())
     
 
-requirements = ['numpy', 'cython', 'matplotlib', 'corner']
+requirements = ['numpy<2', 'cython', 'matplotlib', 'corner']
 
 setup_requirements = ['pytest-runner', ]