diff --git a/Lib/mailbox.py b/Lib/mailbox.py
index eab03af..e66ddde 100755
--- a/Lib/mailbox.py
+++ b/Lib/mailbox.py
@@ -367,12 +367,14 @@
 
     def get_folder(self, folder):
         """Return a Maildir instance for the named folder."""
-        return Maildir(os.path.join(self._path, '.' + folder), create=False)
+        return Maildir(os.path.join(self._path, '.' + folder),
+                       factory=self._factory,
+                       create=False)
 
     def add_folder(self, folder):
         """Create a folder and return a Maildir instance representing it."""
         path = os.path.join(self._path, '.' + folder)
-        result = Maildir(path)
+        result = Maildir(path, factory=self._factory)
         maildirfolder_path = os.path.join(path, 'maildirfolder')
         if not os.path.exists(maildirfolder_path):
             os.close(os.open(maildirfolder_path, os.O_CREAT | os.O_WRONLY))
@@ -944,11 +946,13 @@
 
     def get_folder(self, folder):
         """Return an MH instance for the named folder."""
-        return MH(os.path.join(self._path, folder), create=False)
+        return MH(os.path.join(self._path, folder),
+                  factory=self._factory, create=False)
 
     def add_folder(self, folder):
         """Create a folder and return an MH instance representing it."""
-        return MH(os.path.join(self._path, folder))
+        return MH(os.path.join(self._path, folder),
+                  factory=self._factory)
 
     def remove_folder(self, folder):
         """Delete the named folder, which must be empty."""
diff --git a/Lib/test/test_mailbox.py b/Lib/test/test_mailbox.py
index 40cf192..aaf4097 100644
--- a/Lib/test/test_mailbox.py
+++ b/Lib/test/test_mailbox.py
@@ -673,6 +673,19 @@
         self._box.lock()
         self._box.unlock()
 
+    def test_folder (self):
+        # Test for bug #1569790: verify that folders returned by .get_folder()
+        # use the same factory function.
+        def dummy_factory (s):
+            return None
+        box = self._factory(self._path, factory=dummy_factory)
+        folder = box.add_folder('folder1')
+        self.assert_(folder._factory is dummy_factory)
+        
+        folder1_alias = box.get_folder('folder1')
+        self.assert_(folder1_alias._factory is dummy_factory)
+
+        
 
 class _TestMboxMMDF(TestMailbox):
 
@@ -789,7 +802,11 @@
 
     def test_get_folder(self):
         # Open folders
-        self._box.add_folder('foo.bar')
+        def dummy_factory (s):
+            return None
+        self._box = self._factory(self._path, dummy_factory)
+        
+        new_folder = self._box.add_folder('foo.bar')
         folder0 = self._box.get_folder('foo.bar')
         folder0.add(self._template % 'bar')
         self.assert_(os.path.isdir(os.path.join(self._path, 'foo.bar')))
@@ -797,6 +814,11 @@
         self.assert_(folder1.get_string(folder1.keys()[0]) == \
                      self._template % 'bar')
 
+        # Test for bug #1569790: verify that folders returned by .get_folder()
+        # use the same factory function.
+        self.assert_(new_folder._factory is self._box._factory)
+        self.assert_(folder0._factory is self._box._factory)
+
     def test_add_and_remove_folders(self):
         # Delete folders
         self._box.add_folder('one')