diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index d1352129..8a4a9c8 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -553,6 +553,8 @@
 	hash_size = min(origin_dev_size, cow_dev_size) >> s->store->chunk_shift;
 	hash_size = min(hash_size, max_buckets);
 
+	if (hash_size < 64)
+		hash_size = 64;
 	hash_size = rounddown_pow_of_two(hash_size);
 	if (init_exception_table(&s->complete, hash_size,
 				 DM_CHUNK_CONSECUTIVE_BITS))