diff --git a/heat/engine/resources/autoscaling.py b/heat/engine/resources/autoscaling.py
index 31914023a1..3eb0d8f266 100644
--- a/heat/engine/resources/autoscaling.py
+++ b/heat/engine/resources/autoscaling.py
@@ -392,7 +392,7 @@ class LaunchConfiguration(resource.Resource):
                          'Required': True},
         'KeyName': {'Type': 'String'},
         'UserData': {'Type': 'String'},
-        'SecurityGroups': {'Type': 'String'},
+        'SecurityGroups': {'Type': 'List'},
         'KernelId': {'Type': 'String',
                      'Implemented': False},
         'RamDiskId': {'Type': 'String',