diff --git a/lib/ansible/inventory/__init__.py b/lib/ansible/inventory/__init__.py
index 59a3c37bf9..14cd169265 100644
--- a/lib/ansible/inventory/__init__.py
+++ b/lib/ansible/inventory/__init__.py
@@ -195,8 +195,8 @@ class Inventory(object):
             if self._restriction is not None:
                 hosts = [ h for h in hosts if h in self._restriction ]
 
-        HOSTS_PATTERNS_CACHE[pattern_hash] = hosts[:]
-        return list(set(hosts))
+        HOSTS_PATTERNS_CACHE[pattern_hash] = list(set(hosts))
+        return HOSTS_PATTERNS_CACHE[pattern_hash][:]
 
     @classmethod
     def split_host_pattern(cls, pattern):