diff --git a/os_client_config/config.py b/os_client_config/config.py
index 89b5c6c..96d7f53 100644
--- a/os_client_config/config.py
+++ b/os_client_config/config.py
@@ -19,6 +19,7 @@ import collections
 import copy
 import json
 import os
+import re
 import sys
 import warnings
 
@@ -146,7 +147,9 @@ def _fix_argv(argv):
     # over the place.
     processed = collections.defaultdict(list)
     for index in range(0, len(argv)):
-        if argv[index].startswith('--'):
+        # If the value starts with '--' and has '-' or '_' in it, then
+        # it's worth looking at it
+        if re.match('^--.*(_|-)+.*', argv[index]):
             split_args = argv[index].split('=')
             orig = split_args[0]
             new = orig.replace('_', '-')
diff --git a/os_client_config/tests/test_config.py b/os_client_config/tests/test_config.py
index dcc841a..09a11d2 100644
--- a/os_client_config/tests/test_config.py
+++ b/os_client_config/tests/test_config.py
@@ -702,6 +702,17 @@ class TestConfigArgparse(base.TestCase):
         self.assertEqual(cc.config['auth']['password'], 'pass')
         self.assertEqual(cc.config['auth']['auth_url'], 'auth-url')
 
+    def test_argparse_action_append_no_underscore(self):
+        c = config.OpenStackConfig(config_files=[self.no_yaml],
+                                   vendor_files=[self.no_yaml],
+                                   secure_files=[self.no_yaml])
+        parser = argparse.ArgumentParser()
+        parser.add_argument('--foo', action='append')
+        argv = ['--foo', '1', '--foo', '2']
+        c.register_argparse_arguments(parser, argv=argv)
+        opts, _remain = parser.parse_known_args(argv)
+        self.assertEqual(opts.foo, ['1', '2'])
+
     def test_argparse_underscores_duplicate(self):
         c = config.OpenStackConfig(config_files=[self.no_yaml],
                                    vendor_files=[self.no_yaml],