diff --git a/requests/utils.py b/requests/utils.py
index a24327e9..f31cad88 100644
--- a/requests/utils.py
+++ b/requests/utils.py
@@ -296,13 +296,13 @@ def unicode_from_html(content):
 
 def stream_decode_response_unicode(iterator, r):
     """Stream decodes a iterator."""
-    encoding = get_encoding_from_headers(r.headers)
-    if encoding is None:
+
+    if r.encoding is None:
         for item in iterator:
             yield item
         return
 
-    decoder = codecs.getincrementaldecoder(encoding)(errors='replace')
+    decoder = codecs.getincrementaldecoder(r.encoding)(errors='replace')
     for chunk in iterator:
         rv = decoder.decode(chunk)
         if rv: