--- lib/blkid/probe.c
+++ lib/blkid/probe.c
@@ -422,7 +422,7 @@
 	blocksize = blkid_le16(rs->rs_blocksize);
 
 	/* If the superblock is inside the journal, we have the wrong one */
-	if (id->bim_kboff/(blocksize>>10) > blkid_le32(rs->rs_journal_block))
+	if ((blocksize>>10) && id->bim_kboff/(blocksize>>10) > blkid_le32(rs->rs_journal_block))
 		return -BLKID_ERR_BIG;
 
 	/* LABEL/UUID are only valid for later versions of Reiserfs v3.6. */