diff --git a/cddl/contrib/opensolaris/cmd/zdb/zdb.c b/cddl/contrib/opensolaris/cmd/zdb/zdb.c
index f7cacaa997f3..b82b0344a2d6 100644
--- a/cddl/contrib/opensolaris/cmd/zdb/zdb.c
+++ b/cddl/contrib/opensolaris/cmd/zdb/zdb.c
@@ -1461,6 +1461,11 @@ dump_deadlist(dsl_deadlist_t *dl)
 	if (dump_opt['d'] < 3)
 		return;
 
+	if (dl->dl_oldfmt) {
+		dump_bpobj(&dl->dl_bpobj, "old-format deadlist", 0);
+		return;
+	}
+
 	zdb_nicenum(dl->dl_phys->dl_used, bytes);
 	zdb_nicenum(dl->dl_phys->dl_comp, comp);
 	zdb_nicenum(dl->dl_phys->dl_uncomp, uncomp);