diff --git a/ffmpeg/_run.py b/ffmpeg/_run.py
index c5a2b52..1222853 100644
--- a/ffmpeg/_run.py
+++ b/ffmpeg/_run.py
@@ -1,10 +1,9 @@
 from __future__ import unicode_literals
-
 from .dag import get_outgoing_edges, topo_sort
 from ._utils import basestring
 from builtins import str
 from functools import reduce
-from past.builtins import basestring
+import collections
 import copy
 import operator
 import subprocess
@@ -123,6 +122,11 @@ def _get_output_args(node, stream_name_map):
     fmt = kwargs.pop('format', None)
     if fmt:
         args += ['-f', fmt]
+    if 'video_size' in kwargs:
+        video_size = kwargs.pop('video_size')
+        if not isinstance(video_size, basestring) and isinstance(video_size, collections.Iterable):
+            video_size = '{}x{}'.format(video_size[0], video_size[1])
+        args += ['-video_size', video_size]
     args += _convert_kwargs_to_cmd_line_args(kwargs)
     args += [filename]
     return args
diff --git a/ffmpeg/tests/test_ffmpeg.py b/ffmpeg/tests/test_ffmpeg.py
index 25aedd1..ceb94a1 100644
--- a/ffmpeg/tests/test_ffmpeg.py
+++ b/ffmpeg/tests/test_ffmpeg.py
@@ -237,6 +237,17 @@ def test_filter_asplit():
     ]
 
 
+@pytest.mark.parametrize('video_size', [(320, 240), '320x240'])
+def test__output__video_size(video_size):
+    args = (
+        ffmpeg
+        .input('in')
+        .output('out', video_size=video_size)
+        .get_args()
+    )
+    assert args == ['-i', 'in', '-video_size', '320x240', 'out']
+
+
 def test_filter_normal_arg_escape():
     """Test string escaping of normal filter args (e.g. ``font`` param of ``drawtext`` filter)."""
     def _get_drawtext_font_repr(font):