diff --git a/action_processor.h b/action_processor.h
index b3cc67b..121e0e1 100644
--- a/action_processor.h
+++ b/action_processor.h
@@ -80,6 +80,8 @@
 // ActionProcessor to register itself.
 class ActionProcessorDelegate {
  public:
+  virtual ~ActionProcessorDelegate() = default;
+
   // Called when all processing in an ActionProcessor has completed. A pointer
   // to the ActionProcessor is passed. |code| is set to the exit code of the
   // last completed action.