diff --git a/lib/libdisk/write_pc98_disk.c b/lib/libdisk/write_pc98_disk.c
index c6dc81616cb..e68b85f4b51 100644
--- a/lib/libdisk/write_pc98_disk.c
+++ b/lib/libdisk/write_pc98_disk.c
@@ -15,6 +15,7 @@ __FBSDID("$FreeBSD$");
 #include <unistd.h>
 #include <fcntl.h>
 #include <string.h>
+#include <err.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/ioctl.h>