diff --git a/listings/listing_9.3.cpp b/listings/listing_9.3.cpp
index 47278c2..7a963dc 100644
--- a/listings/listing_9.3.cpp
+++ b/listings/listing_9.3.cpp
@@ -2,6 +2,14 @@
 #include <future>
 #include <thread>
 
+template <typename _ForwardIt, typename _Tp>
+struct accumulate_block {
+    _Tp operator() (_ForwardIt __first, _ForwardIt __last)
+    {
+        return std::accumulate(__first, __last, __Tp{});
+    }
+};
+
 template<typename Iterator,typename T>
 T parallel_accumulate(Iterator first,Iterator last,T init)
 {
@@ -21,7 +29,9 @@ T parallel_accumulate(Iterator first,Iterator last,T init)
     {
         Iterator block_end=block_start;
         std::advance(block_end,block_size);
-        futures[i]=pool.submit(accumulate_block<Iterator,T>());
+        futures[i]=pool.submit([=] {
+            return accumulate_block<Iterator,T>()(block_start,block_end);
+        });
         block_start=block_end;
     }
     T last_result=accumulate_block()(block_start,last);