diff --git a/listings/listing_9.2.cpp b/listings/listing_9.2.cpp
index bb32073..9f7e37a 100644
--- a/listings/listing_9.2.cpp
+++ b/listings/listing_9.2.cpp
@@ -3,7 +3,6 @@
 #include <memory>
 #include <functional>
 #include <iostream>
-#include <iostream>
 
 class function_wrapper
 {