Index: setup/__init__.py
--- setup/__init__.py.orig
+++ setup/__init__.py
@@ -22,7 +22,8 @@ ismacos = 'darwin' in sys.platform
 isfreebsd = 'freebsd' in sys.platform
 isnetbsd = 'netbsd' in sys.platform
 isdragonflybsd = 'dragonfly' in sys.platform
-isbsd = isnetbsd or isfreebsd or isdragonflybsd
+isopenbsd = 'openbsd' in sys.platform
+isbsd = isnetbsd or isfreebsd or isopenbsd or isdragonflybsd
 ishaiku = 'haiku1' in sys.platform
 islinux = not ismacos and not iswindows and not isbsd and not ishaiku
 is_ci = os.environ.get('CI', '').lower() == 'true'
