--- zstd-1.4.4/programs/platform.h.orig	2020-01-06 07:28:37.141195500 +0100
+++ zstd-1.4.4/programs/platform.h	2020-01-06 07:28:47.173254300 +0100
@@ -90,7 +90,7 @@
      && ( defined(__unix__) || defined(__unix) \
        || defined(__midipix__) || defined(__VMS) || defined(__HAIKU__) )
 
-#    if defined(__linux__) || defined(__linux)
+#    if defined(__linux__) || defined(__linux) || defined(__CYGWIN__)
 #      ifndef _POSIX_C_SOURCE
 #        define _POSIX_C_SOURCE 200809L  /* feature test macro : https://www.gnu.org/software/libc/manual/html_node/Feature-Test-Macros.html */
 #      endif
@@ -114,11 +114,11 @@
 ************************************************/
 #if (defined(__linux__) && (PLATFORM_POSIX_VERSION > 1)) \
  || (PLATFORM_POSIX_VERSION >= 200112L) \
- || defined(__DJGPP__) \
- || defined(__MSYS__)
+ || defined(__DJGPP__)
 #  include <unistd.h>   /* isatty */
+#  include <stdio.h>   /* fileno */
 #  define IS_CONSOLE(stdStream) isatty(fileno(stdStream))
-#elif defined(MSDOS) || defined(OS2) || defined(__CYGWIN__)
+#elif defined(MSDOS) || defined(OS2)
 #  include <io.h>       /* _isatty */
 #  define IS_CONSOLE(stdStream) _isatty(_fileno(stdStream))
 #elif defined(WIN32) || defined(_WIN32)