diff --git a/openstackclient/common/utils.py b/openstackclient/common/utils.py
index 42630d913a..783ca8c050 100644
--- a/openstackclient/common/utils.py
+++ b/openstackclient/common/utils.py
@@ -154,14 +154,15 @@ def format_dict(data):
     return output[:-2]
 
 
-def format_list(data):
+def format_list(data, separator=', '):
     """Return a formatted strings
 
     :param data: a list of strings
-    :rtype: a string formatted to a,b,c
+    :param separator: the separator to use between strings (default: ', ')
+    :rtype: a string formatted based on separator
     """
 
-    return ', '.join(sorted(data))
+    return separator.join(sorted(data))
 
 
 def get_field(item, field):
diff --git a/openstackclient/compute/v2/security_group.py b/openstackclient/compute/v2/security_group.py
index e3f542b564..a6f060f60c 100644
--- a/openstackclient/compute/v2/security_group.py
+++ b/openstackclient/compute/v2/security_group.py
@@ -390,7 +390,7 @@ class ShowSecurityGroup(show.ShowOne):
 
         # Format rules into a list of strings
         info.update(
-            {'rules': rules}
+            {'rules': utils.format_list(rules, separator='\n')}
         )
         # Map 'tenant_id' column to 'project_id'
         info.update(
diff --git a/openstackclient/tests/common/test_utils.py b/openstackclient/tests/common/test_utils.py
index b564ffab48..064ad417e6 100644
--- a/openstackclient/tests/common/test_utils.py
+++ b/openstackclient/tests/common/test_utils.py
@@ -347,3 +347,10 @@ class TestFindResource(test_utils.TestCase):
         expected = 'a, b, c'
         self.assertEqual(expected, utils.format_list(['a', 'b', 'c']))
         self.assertEqual(expected, utils.format_list(['c', 'b', 'a']))
+
+    def test_format_list_separator(self):
+        expected = 'a\nb\nc'
+        actual_pre_sorted = utils.format_list(['a', 'b', 'c'], separator='\n')
+        actual_unsorted = utils.format_list(['c', 'b', 'a'], separator='\n')
+        self.assertEqual(expected, actual_pre_sorted)
+        self.assertEqual(expected, actual_unsorted)