diff --git a/setup/build.py b/setup/build.py
index 4268d19bce..17e63d121a 100644
--- a/setup/build.py
+++ b/setup/build.py
@@ -103,7 +103,7 @@ def is_ext_allowed(ext):
     only = ext.get('only', '')
     if only:
         only = set(only.split())
-        q = set(filter(lambda x: globals()["is" + x], ["bsd", "freebsd", "haiku", "linux", "osx", "windows"]))
+        q = set(filter(lambda x: globals()["is" + x], ["bsd", "freebsd", "haiku", "linux", "macos", "windows"]))
         return len(q.intersection(only)) > 0
     return True