diff --git a/review/simpletest/pifr_simpletest.client.inc b/review/simpletest/pifr_simpletest.client.inc
index 39f7166..04586ef 100644
--- a/review/simpletest/pifr_simpletest.client.inc
+++ b/review/simpletest/pifr_simpletest.client.inc
@@ -120,6 +120,11 @@ class pifr_client_review_pifr_simpletest extends pifr_client_review_pifr_drupal
     // Assumes it is currently outside of checkout directory.
     $test_list = $this->test_list();
 
+    // If passed a --file argument, make sure it has tests.
+    if ($test_list == '--file ') {
+      $this->set_error(array('@reason' => t('No valid tests were specified (passed an empty --file argument)')));
+    }
+
     // Run tests from command line.
     chdir($this->checkout_directory);