Needs prototype for close()
diff --git a/util-linux/freeramdisk.c b/util-linux/freeramdisk.c
index af00c66..38267e6 100644
--- a/util-linux/freeramdisk.c
+++ b/util-linux/freeramdisk.c
@@ -27,6 +27,7 @@
 #include <fcntl.h>
 #include <sys/ioctl.h>
 #include <stdlib.h>
+#include <unistd.h>
 #include "busybox.h"