diff --git a/setup.py b/setup.py
index b1eda7ad3d1a1a5be005b4b3d6371afa1f734728..950d190905d6fac6d73f5968579cc5d23e6ef4f6 100644
--- a/setup.py
+++ b/setup.py
@@ -151,7 +151,7 @@ setuptools.setup(
     version=version_,
     python_requires='>=3.6',
 
-    install_requires=[],
+    install_requires=['numpy'],
     setup_requires=[],
     zip_safe=False,
     ext_modules=[cmake_extension('arbor')],