diff --git a/lib/ansible/plugins/inventory/yaml.py b/lib/ansible/plugins/inventory/yaml.py
index 612e5174bb0..3934c2167f3 100644
--- a/lib/ansible/plugins/inventory/yaml.py
+++ b/lib/ansible/plugins/inventory/yaml.py
@@ -138,7 +138,7 @@ class InventoryModule(BaseFileInventoryPlugin):
                 if 'hosts' in group_data:
                     for host_pattern in group_data['hosts']:
                         hosts, port = self._parse_host(host_pattern)
-                        self.populate_host_vars(hosts, group_data['hosts'][host_pattern], group, port)
+                        self.populate_host_vars(hosts, group_data['hosts'][host_pattern] or {}, group, port)
         else:
             self.display.warning("Skipping '%s' as this is not a valid group name" % group)