diff --git a/linux-user/ioctls.h b/linux-user/ioctls.h
index d508d0c04a..3b41128fd7 100644
--- a/linux-user/ioctls.h
+++ b/linux-user/ioctls.h
@@ -102,6 +102,7 @@
      IOCTL(BLKRAGET, IOC_R, MK_PTR(TYPE_LONG))
      IOCTL(BLKSSZGET, IOC_R, MK_PTR(TYPE_INT))
      IOCTL(BLKBSZGET, IOC_R, MK_PTR(TYPE_INT))
+     IOCTL(BLKBSZSET, IOC_W, MK_PTR(TYPE_INT))
      IOCTL_SPECIAL(BLKPG, IOC_W, do_ioctl_blkpg,
                    MK_PTR(MK_STRUCT(STRUCT_blkpg_ioctl_arg)))