diff -r 15835311b5e6 Modules/_multiprocessing/semaphore.c
--- a/Modules/_multiprocessing/semaphore.c	Fri Jul 22 12:15:29 2016 +0200
+++ b/Modules/_multiprocessing/semaphore.c	Sat Jul 23 01:08:54 2016 +1000
@@ -65,7 +65,7 @@
     double timeout;
     PyObject *timeout_obj = Py_None;
     DWORD res, full_msecs, nhandles;
-    HANDLE handles[2], sigint_event;
+    HANDLE handles[2], sigint_event = NULL;
 
     static char *kwlist[] = {"block", "timeout", NULL};