diff --git a/Changelog.rst b/Changelog.rst
index 781e252..0b485ee 100644
--- a/Changelog.rst
+++ b/Changelog.rst
@@ -17,6 +17,8 @@ OfflineIMAP v6.5.6.1 (YYYY-MM-DD)
 
 * Various fixes in documentation.
 
+* Fix unbounded recursion during flag update (Josh Berry).
+
 
 OfflineIMAP v6.5.6 (2014-05-14)
 ===============================
diff --git a/offlineimap/folder/IMAP.py b/offlineimap/folder/IMAP.py
index 05e0a36..e317baf 100644
--- a/offlineimap/folder/IMAP.py
+++ b/offlineimap/folder/IMAP.py
@@ -801,9 +801,9 @@ class IMAPFolder(BaseFolder):
     def __processmessagesflags(self, operation, uidlist, flags):
         # Hack for those IMAP servers with a limited line length
         batch_size = 100
-        while len(uidlist):
-            self.__processmessagesflags_real(operation, uidlist[:batch_size], flags)
-            uidlist = uidlist[batch_size:]
+        for i in xrange(0, len(uidlist), batch_size):
+            self.__processmessagesflags_real(operation,
+              uidlist[i:i + batch_size], flags)
         return