commit https://github.com/vim/vim/commit/d807036d10615b960c814ef3890ecad335b57f56 Author: Bram Moolenaar <Bram@vim.org> Date: Mon Feb 15 21:56:54 2016 +0100 patch 7.4.1324 Problem: Channels with pipes don't work on MS-Windows. Solution: Add pipe I/O support. (Yasuhiro Matsumoto)

--- a/src/vim.h
+++ b/src/vim.h
@@ -1730,7 +1730,7 @@ typedef struct timeval proftime_T;
 typedef int proftime_T;	    /* dummy for function prototypes */
 #endif
 
-#ifdef WIN64
+#ifdef _WIN64
 typedef __int64 sock_T;
 #else
 typedef int sock_T;