diff --git a/listings/listing_7.3.cpp b/listings/listing_7.3.cpp
index 29a85de..228e2e3 100644
--- a/listings/listing_7.3.cpp
+++ b/listings/listing_7.3.cpp
@@ -23,9 +23,9 @@ class lock_free_stack
     }
     std::shared_ptr<T> pop()
     {
-        node* old_head=head.load();
-        while(old_head &&
-              !head.compare_exchange_weak(old_head,old_head->next));
-        return old_head ? old_head->data : std::shared_ptr<T>();
+        if (!head_) { return std::shared_ptr<T>(); }
+        node* original_head=head.load();
+        while(!head.compare_exchange_weak(original_head,original_head->next));
+        return original_head->data;
     }
 };