diff --git a/tests/external_test.php b/tests/external_test.php
index b2ed162..d88e3e8 100644
--- a/tests/external_test.php
+++ b/tests/external_test.php
@@ -37,6 +37,7 @@
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  *
  * @covers \block_townsquare\external::record_usersettings
+ * @runTestsInSeparateProcesses
  */
 class external_test extends \advanced_testcase {