diff --git a/setup.cfg b/setup.cfg
index 9a58b6f..90cc2f5 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -30,7 +30,7 @@ packages =
     trsfile.engine
     trsfile.converters
 install_requires =
-    numpy
+    numpy>=1,<2
 include_package_data = True
 
 [options.extras_require]