diff --git a/django/middleware/gzip.py b/django/middleware/gzip.py
index 7d860abdb1..a7c74481d0 100644
--- a/django/middleware/gzip.py
+++ b/django/middleware/gzip.py
@@ -25,4 +25,5 @@ class GZipMiddleware(object):
 
         response.content = compress_string(response.content)
         response['Content-Encoding'] = 'gzip'
+        response['Content-Length'] = str(len(response.content))
         return response