diff --git a/oslo_config/generator.py b/oslo_config/generator.py
index 119fd95..d38ba7f 100644
--- a/oslo_config/generator.py
+++ b/oslo_config/generator.py
@@ -311,7 +311,7 @@ class _OptFormatter(object):
             defaults = _format_defaults(opt)
         for default_str in defaults:
             if default_str:
-                default_str = ' ' + default_str
+                default_str = ' ' + default_str.replace('\n', '\n#    ')
             if minimal:
                 lines.append('%s =%s\n' % (opt.dest, default_str))
             else:
diff --git a/oslo_config/tests/test_generator.py b/oslo_config/tests/test_generator.py
index 71dc9be..3406b63 100644
--- a/oslo_config/tests/test_generator.py
+++ b/oslo_config/tests/test_generator.py
@@ -122,6 +122,9 @@ class GeneratorTestCase(base.BaseTestCase):
         'str_opt_with_space': cfg.StrOpt('str_opt',
                                          default='  foo bar  ',
                                          help='a string with spaces'),
+        'str_opt_multiline': cfg.StrOpt('str_opt',
+                                        default='foo\nbar\nbaz',
+                                        help='a string with newlines'),
         'bool_opt': cfg.BoolOpt('bool_opt',
                                 default=False,
                                 help='a boolean'),
@@ -528,6 +531,19 @@ class GeneratorTestCase(base.BaseTestCase):
 
 # a string with spaces (string value)
 #str_opt = "  foo bar  "
+''')),
+        ('str_opt_multiline',
+         dict(opts=[('test', [(None, [opts['str_opt_multiline']])])],
+              expected='''[DEFAULT]
+
+#
+# From test
+#
+
+# a string with newlines (string value)
+#str_opt = foo
+#    bar
+#    baz
 ''')),
         ('bool_opt',
          dict(opts=[('test', [(None, [opts['bool_opt']])])],