diff --git a/ext/socket/init.c b/ext/socket/init.c
index ffd1c72895..ebc9031150 100644
--- a/ext/socket/init.c
+++ b/ext/socket/init.c
@@ -43,9 +43,9 @@ VALUE
 rsock_init_sock(VALUE sock, int fd)
 {
     rb_io_t *fp;
+#ifndef _WIN32
     struct stat sbuf;
 
-#ifndef _WIN32
     if (fstat(fd, &sbuf) < 0)
         rb_sys_fail(0);
     if (!S_ISSOCK(sbuf.st_mode))