diff --git a/ox/api.py b/ox/api.py
index 6488a2a..85919d1 100644
--- a/ox/api.py
+++ b/ox/api.py
@@ -126,7 +126,7 @@ class API(object):
             tmpname = filename + '.tmp'
             with open(tmpname, 'wb') as fd:
                 r = self._requests_session.get(url)
-                for chunk in iter(lambda: r.read(chunk_size), b''):
+                for chunk in r.iter_content(chunk_size=chunk_size):
                     fd.write(chunk)
             shutil.move(tmpname, filename)