diff --git a/Lib/tarfile.py b/Lib/tarfile.py
index d8d94f0..226d481 100644
--- a/Lib/tarfile.py
+++ b/Lib/tarfile.py
@@ -627,7 +627,7 @@
     def getcomptype(self):
         if self.buf.startswith(b"\037\213\010"):
             return "gz"
-        if self.buf.startswith(b"BZh91"):
+        if self.buf[0:3] == b"BZh" and self.buf[4:10] == b"1AY&SY":
             return "bz2"
         return "tar"