diff --git a/src/routes/api/run.ts b/src/routes/api/run.ts
index 25623d2..a45b967 100644
--- a/src/routes/api/run.ts
+++ b/src/routes/api/run.ts
@@ -62,6 +62,7 @@ const handleSuccessForSubmission = function (result: RunResponse) {
       // send a post request to callback 
       (async () => {
         // 1. upload the result to s3 and get the url
+        const code = result.stderr ? 400 : 200
         const {url} = await upload(result)
 
         // 2. save the url in db
@@ -74,7 +75,7 @@ const handleSuccessForSubmission = function (result: RunResponse) {
         })
 
         // make the callback request
-        await axios.post(job.callback, {id: result.id, outputs: [url]})
+        await axios.post(job.callback, {id: result.id, code, outputs: [url]})
       })()
       break;
   }
@@ -138,6 +139,7 @@ const getRunPoolElement = function (body: RunRequestBody, res: Response): RunPoo
  *  HTTP/1.1 200 OK
  *  {
  *    "id": 10,
+ *    "code": 200,
  *    "outputs": ["http://localhost/judge-submissions/file.json"]
  *  }
  */
diff --git a/src/utils/s3.ts b/src/utils/s3.ts
index 6ccd6c4..490c010 100644
--- a/src/utils/s3.ts
+++ b/src/utils/s3.ts
@@ -5,8 +5,8 @@ import config = require('../../config')
 
 const client = new Minio.Client({
   endPoint: config.S3.endpoint,
-  port: config.S3.port,
-  useSSL: config.S3.ssl,
+  port: +config.S3.port,
+  useSSL: !!config.S3.ssl,
   accessKey: config.S3.accessKey,
   secretKey: config.S3.secretKey,
 })