diff --git a/boffin/run_concurrently.py b/boffin/run_concurrently.py
index 3632aae..65b2bb8 100644
--- a/boffin/run_concurrently.py
+++ b/boffin/run_concurrently.py
@@ -77,8 +77,7 @@ while clear_displays.poll() is None:
     sleep(1)
 
 # Generate the command for executing tests.
-cmd = ("sudo su - thread%s; export DISPLAY=:%s; pybot -C off -K off -d "
-       args.reports_dir + "/%s; exit")
+cmd = 'sudo su thread%s -c "export DISPLAY=:%s; pybot -C off -K off -d %s/%s"'
 if args.resources_dir:
     cmd += " -v resources_path:" + args.resources_dir + " "
 
@@ -90,7 +89,7 @@ if args.tags_list and args.script_name:
     for i, tag in enumerate(args.tags_list):
         xvfb = Xvfb()
         xvfb.start()
-        values = (i, xvfb.vdisplay_num, i, tag)
+        values = (i, xvfb.vdisplay_num, args.reports_dir, i, tag)
         threads.append(Popen(cmd % values, shell=True))
         while len(threads) == args.processes_count:
             wait_for_finished(threads)