diff --git a/set_app_domain.py b/set_app_domain.py
index 8b2c0db1418bc993ebe756ec7d57c790c7c32758..721209b56fb79d294bfcf34ae76b9a0c04f97daf 100755
--- a/set_app_domain.py
+++ b/set_app_domain.py
@@ -24,7 +24,7 @@ class SetAppDomain():
          by using this format: ms-<instance name> (for example ms-msuser).
     domain: The new domain.''' % __file__
     UNIX_USER_PATTERN = r'[a-z0-9\-]+'
-    DOMAIN_PATTERN = r'([a-z0-9\-]+\.)*[a-z0-9\-]+\.[a-z]+'
+    DOMAIN_PATTERN = r'([a-z0-9\-]+\.)*[a-z0-9\-]+(\.[a-z]+){0,1}'
 
     def __init__(self, *args):
         args = list(args)