diff --git a/babel/messages/catalog.py b/babel/messages/catalog.py
index 065ef35fb..ce7d4bb04 100644
--- a/babel/messages/catalog.py
+++ b/babel/messages/catalog.py
@@ -180,8 +180,10 @@ def python_format(self):
         """Whether the message contains Python-style parameters.
 
         >>> Message('foo %(name)s bar').python_format
+        False
+        >>> Message('foo %(name)s bar', flags=['python-format']).python_format
         True
-        >>> Message(('foo %(name)s', 'foo %(name)s')).python_format
+        >>> Message(('foo %(name)s', 'foo %(name)s'), flags=['python-format']).python_format
         True
 
         :type:  `bool`"""
diff --git a/babel/messages/extract.py b/babel/messages/extract.py
index 8f12f9330..6be3f477b 100644
--- a/babel/messages/extract.py
+++ b/babel/messages/extract.py
@@ -282,7 +282,7 @@ def extract(method, fileobj, keywords=DEFAULT_KEYWORDS, comment_tags=(),
     >>> from io import BytesIO
     >>> for message in extract('python', BytesIO(source)):
     ...     print(message)
-    (3, u'Hello, world!', [], None)
+    (3, u'Hello, world!', [], None, set())
 
     :param method: an extraction method (a callable), or
                    a string specifying the extraction method (.e.g. "python");
diff --git a/babel/messages/pofile.py b/babel/messages/pofile.py
index 3485a2ab6..c23a19308 100644
--- a/babel/messages/pofile.py
+++ b/babel/messages/pofile.py
@@ -475,7 +475,7 @@ def write_po(fileobj, catalog, width=76, no_location=False, omit_header=False,
 
     >>> catalog = Catalog()
     >>> catalog.add(u'foo %(name)s', locations=[('main.py', 1)],
-    ...             flags=('fuzzy',))
+    ...             flags=('fuzzy', 'python-format'))
     <Message...>
     >>> catalog.add((u'bar', u'baz'), locations=[('main.py', 3)])
     <Message...>
diff --git a/tests/messages/data/project/i18n/fi_BUGGY/LC_MESSAGES/messages.po b/tests/messages/data/project/i18n/fi_BUGGY/LC_MESSAGES/messages.po
index 0a0745b42..a7fbce54c 100644
--- a/tests/messages/data/project/i18n/fi_BUGGY/LC_MESSAGES/messages.po
+++ b/tests/messages/data/project/i18n/fi_BUGGY/LC_MESSAGES/messages.po
@@ -1,5 +1,6 @@
 msgid ""
 msgstr ""
 
+#, python-format
 msgid "bar %(sign)s"
 msgstr "tanko %(merkki)s"
diff --git a/tests/messages/test_catalog.py b/tests/messages/test_catalog.py
index 8f51e75be..7016c26fa 100644
--- a/tests/messages/test_catalog.py
+++ b/tests/messages/test_catalog.py
@@ -305,8 +305,10 @@ def test_message_pluralizable():
 
 
 def test_message_python_format():
-    assert catalog.Message('foo %(name)s bar').python_format
-    assert catalog.Message(('foo %(name)s', 'foo %(name)s')).python_format
+    assert catalog.Message('foo %(name)s bar', flags={'python-format'}).python_format
+    assert catalog.Message(('foo %(name)s', 'foo %(name)s'), flags={'python-format'}).python_format
+    assert not catalog.Message('foo %(name)s bar').python_format
+    assert not catalog.Message(('foo %(name)s', 'foo %(name)s')).python_format
 
 
 def test_catalog():