diff --git a/leakcheck/dhparam.pem b/leakcheck/dhparam.pem
new file mode 100644
index 0000000..9d33a4a
--- /dev/null
+++ b/leakcheck/dhparam.pem
@@ -0,0 +1,4 @@
+-----BEGIN DH PARAMETERS-----
+MEYCQQDM2LbvAjF5ahXHOUdDR09Vw/7kxjF/euWhNKBqUQQYT7FDSAMCCMq+Jhno
+BKxWEDhlxR1Q1VZ4H/NVTAGtWai7AgEC
+-----END DH PARAMETERS-----
diff --git a/leakcheck/thread-crash.py b/leakcheck/thread-crash.py
new file mode 100644
index 0000000..26048a5
--- /dev/null
+++ b/leakcheck/thread-crash.py
@@ -0,0 +1,70 @@
+# Copyright (C) Jean-Paul Calderone 2008, All rights reserved
+#
+# Stress tester for thread-related bugs in ssl_Connection_send and
+# ssl_Connection_recv in src/ssl/connection.c for usage of a single
+# Connection object simultaneously in multiple threads.  In 0.7 and earlier,
+# this will somewhat reliably cause Python to abort with a "tstate mix-up"
+# almost immediately, due to the incorrect sharing between threads of the
+# `tstate` field of the connection object.
+
+
+from socket import socket
+from threading import Thread
+
+from OpenSSL.SSL import Connection, Context, TLSv1_METHOD
+
+def send(conn):
+    while 1:
+        for i in xrange(1024 * 32):
+            conn.send('x')
+        print 'Sent 32KB on', hex(id(conn))
+
+
+def recv(conn):
+    while 1:
+        for i in xrange(1024 * 64):
+            conn.recv(1)
+        print 'Received 64KB on', hex(id(conn))
+
+
+def main():
+    port = socket()
+    port.bind(('', 0))
+    port.listen(5)
+
+    client = socket()
+    client.setblocking(False)
+    client.connect_ex(port.getsockname())
+    client.setblocking(True)
+
+    server = port.accept()[0]
+
+    clientCtx = Context(TLSv1_METHOD)
+    clientCtx.set_cipher_list('ALL:ADH')
+    clientCtx.load_tmp_dh('dhparam.pem')
+
+    sslClient = Connection(clientCtx, client)
+    sslClient.set_connect_state()
+
+    serverCtx = Context(TLSv1_METHOD)
+    serverCtx.set_cipher_list('ALL:ADH')
+    serverCtx.load_tmp_dh('dhparam.pem')
+
+    sslServer = Connection(serverCtx, server)
+    sslServer.set_accept_state()
+
+    t1 = Thread(target=send, args=(sslClient,))
+    t2 = Thread(target=send, args=(sslServer,))
+    t3 = Thread(target=recv, args=(sslClient,))
+    t4 = Thread(target=recv, args=(sslServer,))
+
+    t1.start()
+    t2.start()
+    t3.start()
+    t4.start()
+    t1.join()
+    t2.join()
+    t3.join()
+    t4.join()
+
+main()
diff --git a/src/ssl/connection.h b/src/ssl/connection.h
index dedb73e..13f42f0 100644
--- a/src/ssl/connection.h
+++ b/src/ssl/connection.h
@@ -42,7 +42,7 @@
     SSL                 *ssl;
     ssl_ContextObj      *context;
     PyObject            *socket;
-    PyThreadState       *tstate;
+    PyThreadState       *tstate; /* This field is no longer used. */
     PyObject            *app_data;
 } ssl_ConnectionObj;
 
diff --git a/src/ssl/ssl.c b/src/ssl/ssl.c
index 7f58771..1f8cbcc 100644
--- a/src/ssl/ssl.c
+++ b/src/ssl/ssl.c
@@ -32,6 +32,8 @@
 
 void **crypto_API;
 
+int _pyOpenSSL_tstate_key;
+
 /* Exceptions defined by the SSL submodule */
 PyObject *ssl_Error,                   /* Base class              */
          *ssl_ZeroReturnError,         /* Used with SSL_get_error */
@@ -201,6 +203,13 @@
     if (!init_ssl_connection(dict))
         goto error;
 
-error:
+#ifdef WITH_THREAD
+    /*
+     * Initialize this module's threading support structures.
+     */
+    _pyOpenSSL_tstate_key = PyThread_create_key();
+#endif
+
+  error:
     ;
 }
diff --git a/src/ssl/ssl.h b/src/ssl/ssl.h
index e8d3e93..9cf0186 100644
--- a/src/ssl/ssl.h
+++ b/src/ssl/ssl.h
@@ -14,6 +14,7 @@
 #define PyOpenSSL_SSL_H_
 
 #include <Python.h>
+#include <pythread.h>
 #include "context.h"
 #include "connection.h"
 #include "../util.h"
@@ -45,6 +46,10 @@
 
 #define ssl_API_pointers          2
 
+#ifdef WITH_THREAD
+extern int _pyOpenSSL_tstate_key;
+#endif /* WITH_THREAD */
+
 #ifdef SSL_MODULE
 
 extern ssl_Context_New_RETURN    ssl_Context_New    ssl_Context_New_PROTO;
diff --git a/src/util.h b/src/util.h
index 592660e..b95e75b 100644
--- a/src/util.h
+++ b/src/util.h
@@ -30,10 +30,21 @@
  * WHERE to save the thread state.
  */
 #ifdef WITH_THREAD
-#  define MY_BEGIN_ALLOW_THREADS(st)    \
-    { st = PyEval_SaveThread(); }
-#  define MY_END_ALLOW_THREADS(st)      \
-    { PyEval_RestoreThread(st); st = NULL; }
+
+/*
+ * Get the current Python threadstate and put it somewhere any code running
+ * in this thread can get it, if it needs to restore the threadstate to run
+ * some Python.
+ */
+#  define MY_BEGIN_ALLOW_THREADS(ignored)                               \
+    PyThread_set_key_value(_pyOpenSSL_tstate_key, PyEval_SaveThread());
+
+/*
+ * Get the previous Python threadstate and restore it.
+ */
+#  define MY_END_ALLOW_THREADS(ignored)                                 \
+    PyEval_RestoreThread(PyThread_get_key_value(_pyOpenSSL_tstate_key));
+
 #else
 #  define MY_BEGIN_ALLOW_THREADS(st)
 #  define MY_END_ALLOW_THREADS(st)      { st = NULL; }