diff --git a/scrapy/contrib_exp/downloadermiddleware/decompression.py b/scrapy/contrib_exp/downloadermiddleware/decompression.py
index 7863e90b0..6d30c1cf3 100644
--- a/scrapy/contrib_exp/downloadermiddleware/decompression.py
+++ b/scrapy/contrib_exp/downloadermiddleware/decompression.py
@@ -26,7 +26,7 @@ class DecompressionMiddleware(object):
 
     def is_tar(self, response):
         try:
-            tar_file = tarfile.open(name='tar.tmp', fileobj=self.archive)
+            tar_file = tarfile.open(fileobj=self.archive)
         except tarfile.ReadError:
             return False
         if tar_file.members: