diff --git a/certbot/tests/util_test.py b/certbot/tests/util_test.py
index 59a4f10b2..60b3089bb 100644
--- a/certbot/tests/util_test.py
+++ b/certbot/tests/util_test.py
@@ -6,6 +6,7 @@ import shutil
 import stat
 import unittest
 
+import configargparse
 import mock
 import six
 from six.moves import reload_module  # pylint: disable=import-error
@@ -368,6 +369,22 @@ class AddDeprecatedArgumentTest(unittest.TestCase):
                 pass
         self.assertTrue("--old-option" not in stdout.getvalue())
 
+    def test_when_configargparse_set(self):
+        '''In configargparse versions < 0.12.0 ACTION_TYPES_THAT_DONT_NEED_A_VALUE is a set.'''
+        orig = configargparse.ACTION_TYPES_THAT_DONT_NEED_A_VALUE
+        configargparse.ACTION_TYPES_THAT_DONT_NEED_A_VALUE = set()
+        self._call("--old-option", 1)
+        self.assertEqual(len(configargparse.ACTION_TYPES_THAT_DONT_NEED_A_VALUE), 1)
+        configargparse.ACTION_TYPES_THAT_DONT_NEED_A_VALUE = orig
+
+    def test_when_configargparse_tuple(self):
+        '''In configargparse versions >= 0.12.0 ACTION_TYPES_THAT_DONT_NEED_A_VALUE is a tuple.'''
+        orig = configargparse.ACTION_TYPES_THAT_DONT_NEED_A_VALUE
+        configargparse.ACTION_TYPES_THAT_DONT_NEED_A_VALUE = tuple()
+        self._call("--old-option", 1)
+        self.assertEqual(len(configargparse.ACTION_TYPES_THAT_DONT_NEED_A_VALUE), 1)
+        configargparse.ACTION_TYPES_THAT_DONT_NEED_A_VALUE = orig
+
 
 class EnforceLeValidity(unittest.TestCase):
     """Test enforce_le_validity."""
diff --git a/certbot/util.py b/certbot/util.py
index e343fdcb1..5eec90b50 100644
--- a/certbot/util.py
+++ b/certbot/util.py
@@ -477,7 +477,12 @@ def add_deprecated_argument(add_argument, argument_name, nargs):
             sys.stderr.write(
                 "Use of {0} is deprecated.\n".format(option_string))
 
-    configargparse.ACTION_TYPES_THAT_DONT_NEED_A_VALUE.add(ShowWarning)
+    # In version 0.12.0 ACTION_TYPES_THAT_DONT_NEED_A_VALUE was changed from a set
+    # to a tuple.
+    if isinstance(configargparse.ACTION_TYPES_THAT_DONT_NEED_A_VALUE, set):
+        configargparse.ACTION_TYPES_THAT_DONT_NEED_A_VALUE.add(ShowWarning)
+    else:
+        configargparse.ACTION_TYPES_THAT_DONT_NEED_A_VALUE += (ShowWarning,)
     add_argument(argument_name, action=ShowWarning,
                  help=argparse.SUPPRESS, nargs=nargs)