--- premake-core-5.0.0-beta2/contrib/libzip/mkstemp.c
+++ premake-core-5.0.0-beta2/contrib/libzip/mkstemp.c
@@ -38,6 +38,7 @@
 #include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <unistd.h>
 #ifdef _WIN32
 #include <io.h>
 #endif
--- premake-core-5.0.0-beta2/contrib/libzip/zip_close.c
+++ premake-core-5.0.0-beta2/contrib/libzip/zip_close.c
@@ -38,6 +38,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
 #ifdef HAVE_STRINGS_H
 #include <strings.h>
 #endif
--- premake-core-5.0.0-beta2/contrib/libzip/zip_fdopen.c
+++ premake-core-5.0.0-beta2/contrib/libzip/zip_fdopen.c
@@ -34,6 +34,7 @@
 
 
 #include "zipint.h"
+#include <unistd.h>