diff --git a/lib/framework/koa.js b/lib/framework/koa.js
index fd19055..091e771 100644
--- a/lib/framework/koa.js
+++ b/lib/framework/koa.js
@@ -108,24 +108,8 @@ function authenticate(passport, name, options, callback) {
       // mock the `req` object
       const req = createReqMock(ctx, options.assignProperty || passport._userProperty || 'user')
 
-      /*
-       * res.end & res.send should basically behave the same
-       * res.end only takes strings (but should be okay for the mock to take more)
-       * res.send can send a buffer, object, array, or string
-       */
       function setBodyAndResolve(content) {
-        switch (typeof content) {
-          case 'Buffer':
-            ctx.body = content.toString()
-            break
-          case 'object':
-            ctx.body = JSON.stringify(content)
-            break
-          case 'string':
-          default:
-            ctx.body = content
-            break
-        }
+        if (content) ctx.body = content
         resolve(false)
       }