diff --git a/core/scripts/run-tests.sh b/core/scripts/run-tests.sh
index 01974c5..b91a784 100755
--- a/core/scripts/run-tests.sh
+++ b/core/scripts/run-tests.sh
@@ -503,7 +503,8 @@ function simpletest_script_setup_database($new = FALSE) {
 function simpletest_script_execute_batch($test_classes) {
   global $args, $test_ids;
 
-  $exit_code = 0;
+  // Keeps track of failures or exceptions during the tests.
+  $has_fails_or_exceptions = FALSE;
 
   // Multi-process execution.
   $children = array();
@@ -522,6 +523,9 @@ function simpletest_script_execute_batch($test_classes) {
       // to fork for them.
       if (is_subclass_of($test_class, 'Drupal\Tests\UnitTestCase')) {
         $exit_code = simpletest_script_run_phpunit($test_id, $test_class);
+        if ($exit_code) {
+          $has_fails_or_exceptions = TRUE;
+        }
         continue;
       }
 
@@ -553,7 +557,7 @@ function simpletest_script_execute_batch($test_classes) {
         // The child exited, unregister it.
         proc_close($child['process']);
         if ($status['exitcode']) {
-          $exit_code = $status['exitcode'];
+          $has_fails_or_exceptions = TRUE;
           echo 'FATAL ' . $child['class'] . ': test runner returned a non-zero error code (' . $status['exitcode'] . ').' . "\n";
           if ($args['die-on-fail']) {
             list($db_prefix, ) = simpletest_last_test_get($child['test_id']);
@@ -574,7 +578,9 @@ function simpletest_script_execute_batch($test_classes) {
       }
     }
   }
-  exit($exit_code);
+  if ($has_fails_or_exceptions) {
+    return SIMPLETEST_SCRIPT_FAILS_OR_ERRORS;
+  }
 }
 
 /**
@@ -621,7 +627,7 @@ function simpletest_script_run_phpunit($test_id, $class) {
       $exit_code = SIMPLETEST_SCRIPT_FAILS_OR_ERRORS;
     }
   }
-  exit($exit_code);
+  return($exit_code);
 }
 
 /**