diff --git a/mode/mbox.py b/mode/mbox.py
index 6ca8a4e..0bec37d 100644
--- a/mode/mbox.py
+++ b/mode/mbox.py
@@ -1,4 +1,4 @@
-import commands, dirutil, grp, mailbox, method, mode, os.path, pwd, re
+import commands, dirutil, grp, mailbox, method, mode, os.path, pwd, re, sys
 import buffer, default, window
 from mode.mutt import MuttGrammar
 from lex import Grammar, PatternRule, RegionRule, PatternGroupRule
@@ -134,7 +134,11 @@ class MboxListBuffer(Buffer):
         f = open(self.path, 'r')
         self.size = len(f.read())
         f.close()
-        self.mbox = mailbox.mbox(self.path)
+        if sys.version_info == 4:
+            fp = open(self.path, 'rb')
+            self.mbox = mailbox.UnixMailbox(fp)
+        else:
+            self.mbox = mailbox.mbox(self.path)
         lines = []
         pos = 1
         msgs = list(self.mbox)