diff --git a/flask/helpers.py b/flask/helpers.py
index 2f446327..b2ea2ce9 100644
--- a/flask/helpers.py
+++ b/flask/helpers.py
@@ -41,6 +41,7 @@ from .signals import message_flashed
 from .globals import session, _request_ctx_stack, _app_ctx_stack, \
      current_app, request
 from ._compat import string_types, text_type
+from unidecode import unidecode
 
 
 # sentinel
@@ -534,8 +535,11 @@ def send_file(filename_or_fp, mimetype=None, as_attachment=False,
         if attachment_filename is None:
             raise TypeError('filename unavailable, required for '
                             'sending as attachment')
+        filename_dict = {
+            'filename': unidecode(attachment_filename),
+            'filename*': "UTF-8''%s" % url_quote(attachment_filename)}
         headers.add('Content-Disposition', 'attachment',
-                    filename=attachment_filename)
+                    **filename_dict)
 
     if current_app.use_x_sendfile and filename:
         if file is not None:
diff --git a/setup.py b/setup.py
index 08995073..2ffe72ed 100644
--- a/setup.py
+++ b/setup.py
@@ -75,6 +75,7 @@ setup(
         'Jinja2>=2.4',
         'itsdangerous>=0.21',
         'click>=2.0',
+        'unidecode',
     ],
     classifiers=[
         'Development Status :: 4 - Beta',
diff --git a/tests/test_helpers.py b/tests/test_helpers.py
index fd448fb8..362b6cfa 100644
--- a/tests/test_helpers.py
+++ b/tests/test_helpers.py
@@ -560,6 +560,17 @@ class TestSendfile(object):
             assert options['filename'] == 'index.txt'
             rv.close()
 
+    def test_attachment_with_utf8_filename(self):
+        app = flask.Flask(__name__)
+        with app.test_request_context():
+            with open(os.path.join(app.root_path, 'static/index.html')) as f:
+                rv = flask.send_file(f, as_attachment=True,
+                                     attachment_filename='Ñandú／pingüino.txt')
+                value, options = \
+                    parse_options_header(rv.headers['Content-Disposition'])
+                assert options == {'filename': 'Nandu/pinguino.txt', 'filename*': "UTF-8''%C3%91and%C3%BA%EF%BC%8Fping%C3%BCino.txt"}
+                rv.close()
+
     def test_static_file(self):
         app = flask.Flask(__name__)
         # default cache timeout is 12 hours
diff --git a/tox.ini b/tox.ini
index 764b4030..3db7b91f 100644
--- a/tox.ini
+++ b/tox.ini
@@ -27,6 +27,7 @@ deps=
     devel: git+https://github.com/pallets/itsdangerous.git
     devel: git+https://github.com/jek/blinker.git
     simplejson: simplejson
+    unidecode
 
 [testenv:docs]
 deps = sphinx