diff --git a/setup.py b/setup.py
index c0dfcb9e..adfd89af 100644
--- a/setup.py
+++ b/setup.py
@@ -153,7 +153,7 @@ def build_extension(self, ext):
         'console_scripts': ['pymatching=pymatching._cli_argv:cli_argv'],
     },
     python_requires=">=3.7",
-    install_requires=['scipy', 'numpy', 'networkx', 'matplotlib'],
+    install_requires=['scipy', 'numpy==1.*', 'networkx', 'matplotlib'],
     # Needed on Windows to avoid the default `build` colliding with Bazel's `BUILD`.
     options={'build': {'build_base': 'python_build_stim'}},
 )