diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c
index a010ff1e5c92..e60e1326376a 100644
--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -1362,8 +1362,10 @@ static int __reserve_metadata_snap(struct dm_pool_metadata *pmd)
 	dm_sm_inc_block(pmd->metadata_sm, THIN_SUPERBLOCK_LOCATION);
 	r = dm_tm_shadow_block(pmd->tm, THIN_SUPERBLOCK_LOCATION,
 			       &sb_validator, &copy, &inc);
-	if (r)
+	if (r) {
+		dm_sm_dec_block(pmd->metadata_sm, THIN_SUPERBLOCK_LOCATION);
 		return r;
+	}
 
 	BUG_ON(!inc);