diff --git a/hosts.py b/hosts.py
index 8b8397e..fd242e4 100755
--- a/hosts.py
+++ b/hosts.py
@@ -120,6 +120,7 @@ def _read_yaml(path):
 
 GROUPS_PATTERN_OPS = {
     "": lambda old, add: old | add,
+    "&": lambda old, add: old & add,
     "!": lambda old, add: old - add,
 }
 GROUPS_PATTERN_OPS_NAMES = "".join(GROUPS_PATTERN_OPS.keys())