1 files changed, 4 insertions, 3 deletions

diff --git a/lib/libstand/cd9660.c b/lib/libstand/cd9660.c
index 621d30d4681e2..87ef6e92a0058 100644
--- a/lib/libstand/cd9660.c
+++ b/lib/libstand/cd9660.c
@@ -262,11 +262,12 @@ buf_read_file(f, buf_p, size_p)
 	size_t *size_p;
 {
 	struct file *fp = (struct file *)f->f_fsdata;
-	daddr_t blkno;
+	daddr_t blkno, blkoff;
 	int rc = 0;
 	size_t read;
 
 	blkno = fp->f_off / ISO_DEFAULT_BLOCK_SIZE + fp->f_bno;
+	blkoff = fp->f_off % ISO_DEFAULT_BLOCK_SIZE;
 
 	if (blkno != fp->f_buf_blkno) {
 		if (fp->f_buf == (char *)0)
@@ -283,8 +284,8 @@ buf_read_file(f, buf_p, size_p)
 		fp->f_buf_blkno = blkno;
 	}
 
-	*buf_p = fp->f_buf + fp->f_off;
-	*size_p = ISO_DEFAULT_BLOCK_SIZE - fp->f_off;
+	*buf_p = fp->f_buf + blkoff;
+	*size_p = ISO_DEFAULT_BLOCK_SIZE - blkoff;
 
 	if (*size_p > fp->f_size - fp->f_off)
 		*size_p = fp->f_size - fp->f_off;