diff --git a/scrapy/responsetypes.py b/scrapy/responsetypes.py
index c212f5706..5b0bc50a5 100644
--- a/scrapy/responsetypes.py
+++ b/scrapy/responsetypes.py
@@ -11,7 +11,7 @@ import six
 
 from scrapy.http import Response
 from scrapy.utils.misc import load_object
-from scrapy.utils.python import isbinarytext
+from scrapy.utils.python import isbinarytext, to_bytes, to_native_str
 
 class ResponseTypes(object):
 
@@ -59,7 +59,7 @@ class ResponseTypes(object):
 
     def from_content_disposition(self, content_disposition):
         try:
-            filename = content_disposition.split(';')[1].split('=')[1]
+            filename = to_native_str(content_disposition).split(';')[1].split('=')[1]
             filename = filename.strip('"\'')
             return self.from_filename(filename)
         except IndexError: