diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 659e7ae4c..f3382fd88 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,8 @@
+2014-07-21  Corinna Vinschen  <corinna@vinschen.de>
+
+	* thread.cc (pthread::init_mainthread): Initialize thread mutex to
+	type PTHREAD_MUTEX_RECURSIVE, just as for any other thread.
+
 2014-07-16  Corinna Vinschen  <corinna@vinschen.de>
 
 	* thread.cc (pthread::create): Handle stackaddr as upper bound address.
diff --git a/winsup/cygwin/thread.cc b/winsup/cygwin/thread.cc
index fc70c3752..dc4faac7c 100644
--- a/winsup/cygwin/thread.cc
+++ b/winsup/cygwin/thread.cc
@@ -358,6 +358,10 @@ pthread::init_mainthread ()
   if (!thread->create_cancel_event ())
     api_fatal ("couldn't create cancel event for main thread");
   VerifyHandle (thread->win32_obj_id);
+  /* Make sure the pthread mutex is recursive.  See comment in
+     pthread::precreate (called only for subsequent pthreads)
+     for a description. */
+  thread->mutex.set_type (PTHREAD_MUTEX_RECURSIVE);
   thread->postcreate ();
 }