diff --git a/src/storage/s3.js b/src/storage/s3.js
index e3d513441..313c27bd2 100644
--- a/src/storage/s3.js
+++ b/src/storage/s3.js
@@ -153,10 +153,10 @@ async function exists(apiConfig, backupFilePath) {
             Key: backupFilePath
         };
 
-        const [error] = await safe(s3.headObject(params).promise());
-        if (!Object.keys(this.httpResponse.headers).some(h => h.startsWith('x-amz'))) throw new BoxError(BoxError.EXTERNAL_ERROR, 'not a s3 endpoint');
+        const [error, response] = await safe(s3.headObject(params).promise());
         if (error && S3_NOT_FOUND(error)) return false;
         if (error) throw new BoxError(BoxError.EXTERNAL_ERROR, `Error headObject ${backupFilePath}. Message: ${error.message} HTTP Code: ${error.code}`);
+        if (!response || typeof response.Metadata !== 'object') throw new BoxError(BoxError.EXTERNAL_ERROR, 'not a s3 endpoint');
 
         return true;
     } else { // list dir contents