Improve definition of Sock_size_t

1 files changed, 7 insertions, 5 deletions

diff --git a/pp_sys.c b/pp_sys.c
index 3b06b9ccb1..00012c315d 100644
--- a/pp_sys.c
+++ b/pp_sys.c
@@ -89,11 +89,13 @@ extern int h_errno;
 #   define vfork fork
 #endif
 
-/* Put this after #includes because <unistd.h> defines _XOPEN_VERSION. */
-#if _XOPEN_VERSION >= 4
-#   define Sock_size_t Size_t
-#else
-#   define Sock_size_t int
+/* Put this after #includes because <unistd.h> defines _XOPEN_*. */
+#ifndef Sock_size_t
+#  if _XOPEN_VERSION >= 5 || defined(_XOPEN_SOURCE_EXTENDED)
+#    define Sock_size_t Size_t
+#  else
+#    define Sock_size_t int
+#  endif
 #endif
 
 #if !defined(HAS_MKDIR) || !defined(HAS_RMDIR)