diff --git a/tablib/compat.py b/tablib/compat.py
index 3e88305..0fac899 100644
--- a/tablib/compat.py
+++ b/tablib/compat.py
@@ -36,7 +36,6 @@ if is_py3:
 
 else:
     from cStringIO import StringIO as BytesIO
-    from cStringIO import StringIO
     import tablib.packages.xlwt as xlwt
     from tablib.packages import markup
     from itertools import ifilter
diff --git a/tablib/formats/_csv.py b/tablib/formats/_csv.py
index 7581246..2e459ff 100644
--- a/tablib/formats/_csv.py
+++ b/tablib/formats/_csv.py
@@ -20,7 +20,7 @@ DEFAULT_ENCODING = 'utf-8'
 
 def export_set(dataset):
     """Returns CSV representation of Dataset."""
-    stream = ()
+    stream = BytesIO()
 
     if is_py3:
         _csv = csv.writer(stream)