diff -Nru twine-3.1.0/debian/changelog twine-3.1.1/debian/changelog
--- twine-3.1.0/debian/changelog	2019-11-27 19:57:17.000000000 +0000
+++ twine-3.1.1/debian/changelog	2019-12-24 07:36:25.000000000 +0000
@@ -1,3 +1,9 @@
+twine (3.1.1-1) unstable; urgency=medium
+
+  * New upstream point release.
+
+ -- Stefano Rivera <stefanor@debian.org>  Tue, 24 Dec 2019 09:36:25 +0200
+
 twine (3.1.0-1) unstable; urgency=medium
 
   * New upstream release.
diff -Nru twine-3.1.0/docs/changelog.rst twine-3.1.1/docs/changelog.rst
--- twine-3.1.0/docs/changelog.rst	2019-11-23 12:56:06.000000000 +0000
+++ twine-3.1.1/docs/changelog.rst	2019-11-27 16:47:19.000000000 +0000
@@ -3,6 +3,9 @@
 =========
 Changelog
 =========
+* :release:`3.1.1 <2019-11-27>`
+* :bug:`548` Restore ``--non-interactive`` as a flag not expecting an
+  argument.
 * :release:`3.1.0 <2019-11-23>`
 * :feature:`547` Add support for specifying ``--non-interactive`` as an
   environment variable.
diff -Nru twine-3.1.0/PKG-INFO twine-3.1.1/PKG-INFO
--- twine-3.1.0/PKG-INFO	2019-11-23 12:56:33.907975400 +0000
+++ twine-3.1.1/PKG-INFO	2019-11-27 16:47:47.881178600 +0000
@@ -1,6 +1,6 @@
 Metadata-Version: 1.2
 Name: twine
-Version: 3.1.0
+Version: 3.1.1
 Summary: Collection of utilities for publishing packages on PyPI
 Home-page: https://twine.readthedocs.io/
 Author: Donald Stufft and individual contributors
diff -Nru twine-3.1.0/tests/test_settings.py twine-3.1.1/tests/test_settings.py
--- twine-3.1.0/tests/test_settings.py	2019-11-23 12:56:06.000000000 +0000
+++ twine-3.1.1/tests/test_settings.py	2019-11-27 16:47:19.000000000 +0000
@@ -14,6 +14,7 @@
 # limitations under the License.
 import os.path
 import textwrap
+import argparse
 
 from twine import exceptions
 from twine import settings
@@ -81,3 +82,24 @@
         username='fakeuser', password='anything', client_cert=client_cert)
     assert not settings_obj.password
     assert settings_obj.client_cert == client_cert
+
+
+class TestArgumentParsing:
+
+    @staticmethod
+    def parse_args(args):
+        parser = argparse.ArgumentParser()
+        settings.Settings.register_argparse_arguments(parser)
+        return parser.parse_args(args)
+
+    def test_non_interactive_flag(self):
+        args = self.parse_args(['--non-interactive'])
+        assert args.non_interactive
+
+    def test_non_interactive_environment(self, monkeypatch):
+        monkeypatch.setenv("TWINE_NON_INTERACTIVE", "1")
+        args = self.parse_args([])
+        assert args.non_interactive
+        monkeypatch.setenv("TWINE_NON_INTERACTIVE", "0")
+        args = self.parse_args([])
+        assert not args.non_interactive
diff -Nru twine-3.1.0/twine/settings.py twine-3.1.1/twine/settings.py
--- twine-3.1.0/twine/settings.py	2019-11-23 12:56:06.000000000 +0000
+++ twine-3.1.1/twine/settings.py	2019-11-27 16:47:19.000000000 +0000
@@ -201,10 +201,8 @@
         )
         parser.add_argument(
             "--non-interactive",
-            action=utils.EnvironmentDefault,
+            action=utils.EnvironmentFlag,
             env="TWINE_NON_INTERACTIVE",
-            default=False,
-            required=False,
             help="Do not interactively prompt for username/password if the "
                  "required credentials are missing. (Can also be set via "
                  "%(env)s environment variable.)"
diff -Nru twine-3.1.0/twine/utils.py twine-3.1.1/twine/utils.py
--- twine-3.1.0/twine/utils.py	2019-11-23 12:56:06.000000000 +0000
+++ twine-3.1.1/twine/utils.py	2019-11-27 16:47:19.000000000 +0000
@@ -233,3 +233,27 @@
 
     def __call__(self, parser, namespace, values, option_string=None):
         setattr(namespace, self.dest, values)
+
+
+class EnvironmentFlag(argparse.Action):
+    """Set boolean flag from environment variable."""
+
+    def __init__(
+        self,
+        env: str,
+        **kwargs
+    ) -> None:
+        default = self.bool_from_env(os.environ.get(env))
+        self.env = env
+        super().__init__(default=default, nargs=0, **kwargs)
+
+    def __call__(self, parser, namespace, values, option_string=None):
+        setattr(namespace, self.dest, True)
+
+    @staticmethod
+    def bool_from_env(val):
+        """
+        Allow '0' and 'false' and 'no' to be False
+        """
+        falsey = {'0', 'false', 'no'}
+        return val and val.lower() not in falsey
diff -Nru twine-3.1.0/twine.egg-info/PKG-INFO twine-3.1.1/twine.egg-info/PKG-INFO
--- twine-3.1.0/twine.egg-info/PKG-INFO	2019-11-23 12:56:33.000000000 +0000
+++ twine-3.1.1/twine.egg-info/PKG-INFO	2019-11-27 16:47:47.000000000 +0000
@@ -1,6 +1,6 @@
 Metadata-Version: 1.2
 Name: twine
-Version: 3.1.0
+Version: 3.1.1
 Summary: Collection of utilities for publishing packages on PyPI
 Home-page: https://twine.readthedocs.io/
 Author: Donald Stufft and individual contributors