diff --git a/database/upgrades/00-latest-revision.sql b/database/upgrades/00-latest-revision.sql
index 107979a..08e7b88 100644
--- a/database/upgrades/00-latest-revision.sql
+++ b/database/upgrades/00-latest-revision.sql
@@ -1,4 +1,4 @@
--- v0 -> v18: Latest revision
+-- v0 -> v18 (compatible with v15+): Latest revision
 
 CREATE TABLE guild (
     dcid       TEXT PRIMARY KEY,
diff --git a/database/upgrades/18-extra-ghost-metadata.sql b/database/upgrades/18-extra-ghost-metadata.sql
index ed95f86..92677dc 100644
--- a/database/upgrades/18-extra-ghost-metadata.sql
+++ b/database/upgrades/18-extra-ghost-metadata.sql
@@ -1,4 +1,4 @@
--- v18: Store additional metadata for ghosts
+-- v18 (compatible with v15+): Store additional metadata for ghosts
 ALTER TABLE puppet ADD COLUMN username TEXT NOT NULL DEFAULT '';
 ALTER TABLE puppet ADD COLUMN discriminator TEXT NOT NULL DEFAULT '';
 ALTER TABLE puppet ADD COLUMN is_bot BOOLEAN NOT NULL DEFAULT false;