diff --git a/mode/mbox.py b/mode/mbox.py
index 0bec37d..35f2ee5 100644
--- a/mode/mbox.py
+++ b/mode/mbox.py
@@ -134,7 +134,7 @@ class MboxListBuffer(Buffer):
         f = open(self.path, 'r')
         self.size = len(f.read())
         f.close()
-        if sys.version_info == 4:
+        if sys.version_info[1] == 4:
             fp = open(self.path, 'rb')
             self.mbox = mailbox.UnixMailbox(fp)
         else: