diff --git a/lib/spack/spack/operating_systems/mac_os.py b/lib/spack/spack/operating_systems/mac_os.py
index fa7718f806c..519820f9328 100644
--- a/lib/spack/spack/operating_systems/mac_os.py
+++ b/lib/spack/spack/operating_systems/mac_os.py
@@ -54,6 +54,7 @@ def __init__(self):
             '10.13': 'highsierra',
             '10.14': 'mojave',
             '10.15': 'catalina',
+            '11.0':  'bigsur',
         }
 
         mac_ver = str(macos_version().up_to(2))