diff --git a/scrapy/contrib/downloadermiddleware/httpcompression.py b/scrapy/contrib/downloadermiddleware/httpcompression.py
index 031001f15..26069d437 100644
--- a/scrapy/contrib/downloadermiddleware/httpcompression.py
+++ b/scrapy/contrib/downloadermiddleware/httpcompression.py
@@ -2,7 +2,7 @@ import zlib
from gzip import GzipFile
from cStringIO import StringIO
-from scrapy.http import Response
+from scrapy.http import Response, TextResponse
from scrapy.core.downloader.responsetypes import responsetypes
@@ -21,7 +21,12 @@ class HttpCompressionMiddleware(object):
decoded_body = self._decode(response.body, encoding.lower())
respcls = responsetypes.from_args(headers=response.headers, \
url=response.url)
- response = response.replace(cls=respcls, body=decoded_body)
+ kwargs = dict(cls=respcls, body=decoded_body)
+ if issubclass(respcls, TextResponse):
+ # force recalculating the encoding until we make sure the
+ # responsetypes guessing is reliable
+ kwargs['encoding'] = None
+ response = response.replace(**kwargs)
if not content_encoding:
del response.headers['Content-Encoding']
diff --git a/scrapy/tests/test_downloadermiddleware_httpcompression.py b/scrapy/tests/test_downloadermiddleware_httpcompression.py
index 40988ecd7..a48ca35a9 100644
--- a/scrapy/tests/test_downloadermiddleware_httpcompression.py
+++ b/scrapy/tests/test_downloadermiddleware_httpcompression.py
@@ -118,3 +118,21 @@ class HttpCompressionTest(TestCase):
self.assertEqual(newresponse.body, plainbody)
self.assertEqual(newresponse.encoding, resolve_encoding('gb2312'))
+ def test_process_response_force_recalculate_encoding(self):
+ headers = {
+ 'Content-Type': 'text/html',
+ 'Content-Encoding': 'gzip',
+ }
+ f = StringIO()
+ plainbody = """Some page"""
+ zf = GzipFile(fileobj=f, mode='wb')
+ zf.write(plainbody)
+ zf.close()
+ response = HtmlResponse("http;//www.example.com/page.html", headers=headers, body=f.getvalue())
+ request = Request("http://www.example.com/")
+
+ newresponse = self.mw.process_response(request, response, self.spider)
+ assert isinstance(newresponse, HtmlResponse)
+ self.assertEqual(newresponse.body, plainbody)
+ self.assertEqual(newresponse.encoding, resolve_encoding('gb2312'))
+