diff --git a/test/adaptor_test/transformed.cpp b/test/adaptor_test/transformed.cpp
index 9146f84..10f6a0c 100644
--- a/test/adaptor_test/transformed.cpp
+++ b/test/adaptor_test/transformed.cpp
@@ -44,6 +44,8 @@ namespace boost
 
         struct lambda
         {
+            typedef int result_type;
+
             lambda(const lambda_init& init) {}
             lambda(const lambda& rhs) {}