diff -Naur a/lib/dgif_lib.c b/lib/dgif_lib.c
--- a/lib/dgif_lib.c	2016-04-02 21:34:00.000000000 +0600
+++ b/lib/dgif_lib.c	2017-04-21 07:06:48.781271400 +0700
@@ -12,7 +12,9 @@
 #include <limits.h>
 #include <stdint.h>
 #include <fcntl.h>
+#ifndef _MSC_VER
 #include <unistd.h>
+#endif
 #include <stdio.h>
 #include <string.h>
 
diff -Naur a/lib/egif_lib.c b/lib/egif_lib.c
--- a/lib/egif_lib.c	2016-01-22 16:36:36.000000000 +0600
+++ b/lib/egif_lib.c	2017-04-21 07:07:08.728159900 +0700
@@ -8,7 +8,9 @@
 
 *****************************************************************************/
 
+#ifndef _MSC_VER
 #include <unistd.h>
+#endif
 #include <stdint.h>
 #include <stdlib.h>
 #include <stdio.h>
diff -Naur a/lib/gif_hash.c b/lib/gif_hash.c
--- a/lib/gif_hash.c	2014-05-16 17:46:53.000000000 +0700
+++ b/lib/gif_hash.c	2017-04-21 07:07:17.718719500 +0700
@@ -11,7 +11,9 @@
 
 *****************************************************************************/
 
+#ifndef _MSC_VER
 #include <unistd.h>
+#endif
 #include <stdint.h>
 #include <stdlib.h>
 #include <fcntl.h>
diff -Naur a/lib/gif_hash.h b/lib/gif_hash.h
--- a/lib/gif_hash.h	2014-05-16 17:46:53.000000000 +0700
+++ b/lib/gif_hash.h	2017-04-21 07:07:32.316346800 +0700
@@ -7,7 +7,9 @@
 #ifndef _GIF_HASH_H_
 #define _GIF_HASH_H_
 
+#ifndef _MSC_VER
 #include <unistd.h>
+#endif
 #include <stdint.h>
 
 #define HT_SIZE			8192	   /* 12bits = 4096 or twice as big! */