diff --git a/app/controllers/submissions_controller.rb b/app/controllers/submissions_controller.rb
index 23531596..b17220dc 100644
--- a/app/controllers/submissions_controller.rb
+++ b/app/controllers/submissions_controller.rb
@@ -184,6 +184,8 @@ class SubmissionsController < ApplicationController
           # Check whether the client send a JSON command and kill container
           # if the command is 'client_kill', send it to docker otherwise.
           begin
+            next if data == "\n"
+
             parsed = JSON.parse(data)
             if parsed.class == Hash && parsed['cmd'] == 'client_kill'
               Rails.logger.debug("Client exited container.")