diff --git a/README.md b/README.md
index b0e3b51..c39e8d0 100644
--- a/README.md
+++ b/README.md
@@ -26,7 +26,7 @@ $ npm install koa-send
  - `index` Name of the index file to serve automatically when visiting the root location. (defaults to none).
  - `gzip` Try to serve the gzipped version of a file automatically when `gzip` is supported by a client and if the requested file with `.gz` extension exists. (defaults to `true`).
  - `brotli` Try to serve the brotli version of a file automatically when `brotli` is supported by a client and if the requested file with `.br` extension exists. (defaults to `true`).
- - `format` If not `false` (defaults to `true`), format the path to serve static file servers and not require a trailing slash for directories, so that you can do both `/directory` and `/directory/`.
+ - `format` If not `false` (defaults to `'follow'`), format the path to serve static file servers and not require a trailing slash for directories, so that you can do both `/directory` and `/directory/` transparently. If it is `'redirect'`, issue a HTTP 302 redirection to the url with trailing slash.
  - [`setHeaders`](#setheaders) Function to set custom headers on response.
  - `extensions` Try to match extensions from passed array to search for file when no extension is sufficed in URL. First found is served. (defaults to `false`)
 
diff --git a/index.js b/index.js
index 18b4a36..a203c22 100644
--- a/index.js
+++ b/index.js
@@ -47,7 +47,7 @@ async function send (ctx, path, opts = {}) {
   const maxage = opts.maxage || opts.maxAge || 0
   const immutable = opts.immutable || false
   const hidden = opts.hidden || false
-  const format = opts.format !== false
+  const format = (opts.format === false) ? false : (opts.format === 'redirect' ? 'redirect' : 'follow')
   const extensions = Array.isArray(opts.extensions) ? opts.extensions : false
   const brotli = opts.brotli !== false
   const gzip = opts.gzip !== false
@@ -107,10 +107,15 @@ async function send (ctx, path, opts = {}) {
     // Format the path to serve static file servers
     // and not require a trailing slash for directories,
     // so that you can do both `/directory` and `/directory/`
+    // for 'follow', transparently send the file
+    // for 'redirect', give HTTP 302 redirection
     if (stats.isDirectory()) {
-      if (format && index) {
+      if (format === 'follow' && index) {
         path += `/${index}`
         stats = await fs.stat(path)
+      } else if (format === 'redirect' && index) {
+        ctx.redirect(ctx.request.path + '/' + ctx.request.search)
+        return true
       } else {
         return
       }