diff --git a/docs/migrate.md b/docs/migrate.md
index fa16bbe68..1a8dfbf37 100644
--- a/docs/migrate.md
+++ b/docs/migrate.md
@@ -76,3 +76,7 @@ git pull --ff
 NODE_ENV=production pnpm run migrate
 # build using prefered method
 ```
+
+## Reverse
+
+You ***cannot*** migrate back to Misskey from Calckey due to re-hashing passwords on signin with argon2. You can migrate from to Calckey to Foundkey, though.