diff --git a/src/Runner.php b/src/Runner.php
index 595fe4d53..823fbee93 100644
--- a/src/Runner.php
+++ b/src/Runner.php
@@ -189,7 +189,8 @@ protected function instantiateCommandClass($commandClass)
             $commandClass = $container->get($commandFileName);
         }
         // If the command class is a Builder Aware Interface, then
-        //
+        // ensure that it has a builder.  Every command class needs
+        // its own collection builder, as they have references to each other.
         if ($commandClass instanceof BuilderAwareInterface) {
             $builder = $container->get('collectionBuilder', [$commandClass]);
             $commandClass->setBuilder($builder);