diff --git a/core/scripts/run-tests.sh b/core/scripts/run-tests.sh
index 5f4b7d1..3733407 100755
--- a/core/scripts/run-tests.sh
+++ b/core/scripts/run-tests.sh
@@ -307,13 +307,13 @@ function simpletest_script_execute_batch($test_classes) {
       if (empty($test_classes)) {
         break;
       }
-      // Do not attempt to execute abstract/base classes.
-      // Abstract/base classes should be filtered out at this point already.
+      // Do not attempt to execute abstract classes.
+      // Abstract classes should be filtered out at this point already.
       // This is the last line of defense.
       // @see simpletest_script_get_test_list()
       $test_class = array_shift($test_classes);
       $class_info = new \ReflectionClass($test_class);
-      if (!$class_info->hasMethod('getInfo')) {
+      if ($class_info->isAbstract()) {
         continue;
       }
 
@@ -557,10 +557,10 @@ function simpletest_script_get_test_list() {
     }
   }
 
-  // Filter out abstract/base classes.
+  // Filter out abstract classes.
   foreach ($test_list as $i => $test_class) {
     $class_info = new \ReflectionClass($test_class);
-    if (!$class_info->hasMethod('getInfo')) {
+    if ($class_info->isAbstract()) {
       unset($test_list[$i]);
     }
   }