diff --git a/include/boost/asio/detail/win_iocp_overlapped_ptr.hpp b/include/boost/asio/detail/win_iocp_overlapped_ptr.hpp
index 2d1a1155..6ac4834f 100644
--- a/include/boost/asio/detail/win_iocp_overlapped_ptr.hpp
+++ b/include/boost/asio/detail/win_iocp_overlapped_ptr.hpp
@@ -147,7 +147,7 @@ private:
     overlapped_operation(const overlapped_operation&);
     void operator=(const overlapped_operation&);
     
-    static void do_completion_impl(operation* op,
+    static void do_completion_impl(win_iocp_io_service::operation* op,
         DWORD last_error, size_t bytes_transferred)
     {
       // Take ownership of the operation object.
@@ -172,7 +172,7 @@ private:
           bind_handler(handler, ec, bytes_transferred), &handler);
     }
 
-    static void destroy_impl(operation* op)
+    static void destroy_impl(win_iocp_io_service::operation* op)
     {
       // Take ownership of the operation object.
       typedef overlapped_operation<Handler> op_type;