diff --git a/Lib/threading.py b/Lib/threading.py
index 860c2fdd33c..61c25b65344 100644
--- a/Lib/threading.py
+++ b/Lib/threading.py
@@ -653,6 +653,7 @@ class _DummyThread(Thread):
 
     def __init__(self):
         Thread.__init__(self, name=_newname("Dummy-%d"))
+        del self._Thread__block
         self._Thread__started = True
         _active_limbo_lock.acquire()
         _active[_get_ident()] = self
diff --git a/Misc/NEWS b/Misc/NEWS
index d7b35d51678..8d00f22a643 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -33,6 +33,11 @@ Extension Modules
 Library
 -------
 
+- _DummyThread objects in the threading module now delete self.__block that is
+  inherited from _Thread since it uses up a lock allocated by 'thread'.  The
+  lock primitives tend to be limited in number and thus should not be wasted on
+  a _DummyThread object.  Fixes bug #1089632.
+
 - The imghdr module now detects Exif files.
 
 - StringIO.truncate() now correctly adjusts the size attribute.