diff --git a/review/simpletest/pifr_simpletest.client.inc b/review/simpletest/pifr_simpletest.client.inc
index 80893e3..baf37e0 100644
--- a/review/simpletest/pifr_simpletest.client.inc
+++ b/review/simpletest/pifr_simpletest.client.inc
@@ -126,6 +126,14 @@ class pifr_client_review_pifr_simpletest extends pifr_client_review_pifr_drupal
     // @TODO: Temporary until #22336 is committed.
     $run_tests = file_exists('scripts/run-tests.sh') ? 'scripts/run-tests.sh' : 'core/scripts/run-tests.sh';
     $url = escapeshellarg(url('', array('absolute' => TRUE)) . 'checkout');
+
+    // Attempt to clear out any tables from previous runs
+    if (!$this->exec(PIFR_CLIENT_PHP . ' ./' . $run_tests . ' --php ' . PIFR_CLIENT_PHP . ' --clean')) {
+      $this->set_error(array('@reason' => t('failed during invocation of run-tests.sh --clean')));
+      return;
+    }
+
+    // Kick off actual testing
     if (!$this->exec(PIFR_CLIENT_PHP . ' ./' . $run_tests . ' --concurrency ' . PIFR_CLIENT_CONCURRENCY .
       ' --php ' . PIFR_CLIENT_PHP . ' --url ' . $url . ' ' . $test_list)) {
       $this->set_error(array('@reason' => t('failed during invocation of run-tests.sh')));