diff --git a/CLAUDE.md b/CLAUDE.md
index b8100b7..51088f5 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -19,6 +19,7 @@ Default to using Bun instead of Node.js.
 - `bun:sqlite` for SQLite. Don't use `better-sqlite3`.
 - `Bun.redis` for Redis. Don't use `ioredis`.
 - `Bun.sql` for Postgres. Don't use `pg` or `postgres.js`.
+- `Bun.S3Client` for S3. Don't use `aws-sdk`.
 - `WebSocket` is built-in. Don't use `ws`.
 - Prefer `Bun.file` over `node:fs`'s readFile/writeFile
 - Bun.$`ls` instead of execa.