--- include/tls.h.orig	2017-02-13 20:19:55.918636579 +0900
+++ include/tls.h	2017-02-13 20:21:18.313073161 +0900
@@ -22,6 +22,13 @@
 extern "C" {
 #endif

+#ifdef _MSC_VER
+#ifndef LIBRESSL_INTERNAL
+#include <basetsd.h>
+typedef SSIZE_T ssize_t;
+#endif
+#endif
+
 #include <sys/types.h>

 #include <stddef.h>
