diff --git a/block/compat_ioctl.c b/block/compat_ioctl.c
index 7f053468b50d..d490ac220ba8 100644
--- a/block/compat_ioctl.c
+++ b/block/compat_ioctl.c
@@ -393,7 +393,7 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 		return 0;
 	case BLKGETSIZE:
 		size = i_size_read(bdev->bd_inode);
-		if ((size >> 9) > ~0UL)
+		if ((size >> 9) > ~(compat_ulong_t)0)
 			return -EFBIG;
 		return compat_put_ulong(arg, size >> 9);