Index: Lib/tarfile.py
===================================================================
--- Lib/tarfile.py	(revision 51424)
+++ Lib/tarfile.py	(working copy)
@@ -411,9 +411,6 @@
             self.buf += self.cmp.flush()
 
         if self.mode == "w" and self.buf:
-            blocks, remainder = divmod(len(self.buf), self.bufsize)
-            if remainder > 0:
-                self.buf += NUL * (self.bufsize - remainder)
             self.fileobj.write(self.buf)
             self.buf = ""
             if self.comptype == "gz":
Index: Lib/test/test_tarfile.py
===================================================================
--- Lib/test/test_tarfile.py	(revision 51424)
+++ Lib/test/test_tarfile.py	(working copy)
@@ -324,6 +324,31 @@
 class WriteStreamTest(WriteTest):
     sep = '|'
 
+    def test_padding(self):
+        self.dst.close()
+
+        if self.comp == "gz":
+            f = gzip.GzipFile(self.dstname)
+            s = f.read()
+            f.close()
+
+        elif self.comp == "bz2":
+            f = bz2.BZ2Decompressor()
+            s = file(self.dstname).read()
+            s = f.decompress(s)
+
+            self.assertEqual(len(f.unused_data), 0,
+                    "trailing data")
+
+        else:
+            f = file(self.dstname)
+            s = f.read()
+            f.close()
+
+        self.assertEqual(s.count("\0"), tarfile.RECORDSIZE,
+                "incorrect zero padding")
+
+
 class WriteGNULongTest(unittest.TestCase):
     """This testcase checks for correct creation of GNU Longname
        and Longlink extensions.