diff --git a/Changelog.rst b/Changelog.rst
index 66f5c05..cdd871f 100644
--- a/Changelog.rst
+++ b/Changelog.rst
@@ -8,6 +8,9 @@ ChangeLog
 OfflineIMAP v6.5.6.1 (YYYY-MM-DD)
 =================================
 
+* Updated bundled imaplib2 to 2.37:
+  - add missing idle_lock in _handler()
+
 * Added default CA bundle location for OpenBSD
   (GitHub pull #120) and DragonFlyBSD.
 
diff --git a/offlineimap/imaplib2.py b/offlineimap/imaplib2.py
index 14a802b..8921c9d 100644
--- a/offlineimap/imaplib2.py
+++ b/offlineimap/imaplib2.py
@@ -17,9 +17,9 @@ Public functions: Internaldate2Time
 __all__ = ("IMAP4", "IMAP4_SSL", "IMAP4_stream",
            "Internaldate2Time", "ParseFlags", "Time2Internaldate")
 
-__version__ = "2.36"
+__version__ = "2.37"
 __release__ = "2"
-__revision__ = "36"
+__revision__ = "37"
 __credits__ = """
 Authentication code contributed by Donn Cave <donn@u.washington.edu> June 1998.
 String method conversion by ESR, February 2001.
@@ -42,7 +42,8 @@ Threads now set the "daemon" flag (suggested by offlineimap-project) April 2011.
 Single quoting introduced with the help of Vladimir Marek <vladimir.marek@oracle.com> August 2011.
 Support for specifying SSL version by Ryan Kavanagh <rak@debian.org> July 2013.
 Fix for gmail "read 0" error provided by Jim Greenleaf <james.a.greenleaf@gmail.com> August 2013.
-Fix for offlineimap "indexerror: string index out of range" bug provided by Eygene Ryabinkin <rea@codelabs.ru> August 2013."""
+Fix for offlineimap "indexerror: string index out of range" bug provided by Eygene Ryabinkin <rea@codelabs.ru> August 2013.
+Fix for missing idle_lock in _handler() provided by Franklin Brook <franklin@brook.se> August 2014"""
 __author__ = "Piers Lauder <piers@janeelix.com>"
 __URL__ = "http://imaplib2.sourceforge.net"
 __license__ = "Python License"
@@ -1663,16 +1664,20 @@ class IMAP4(object):
         typ, val = self.abort, 'connection terminated'
 
         while not self.Terminate:
+
+            self.idle_lock.acquire()
+            if self.idle_timeout is not None:
+                timeout = self.idle_timeout - time.time()
+                if timeout <= 0:
+                    timeout = 1
+                if __debug__:
+                    if self.idle_rqb is not None:
+                        self._log(5, 'server IDLING, timeout=%.2f' % timeout)
+            else:
+                timeout = resp_timeout
+            self.idle_lock.release()
+
             try:
-                if self.idle_timeout is not None:
-                    timeout = self.idle_timeout - time.time()
-                    if timeout <= 0:
-                        timeout = 1
-                    if __debug__:
-                        if self.idle_rqb is not None:
-                            self._log(5, 'server IDLING, timeout=%.2f' % timeout)
-                else:
-                    timeout = resp_timeout
                 line = self.inq.get(True, timeout)
             except Queue.Empty:
                 if self.idle_rqb is None: