diff --git a/libstdc++-v3/testsuite/experimental/net/timer/waitable/dest.cc b/libstdc++-v3/testsuite/experimental/net/timer/waitable/dest.cc
index cff654c05275f78279fdc7f4a094fad95b65bee8..cb818708aef25171465d529ca08af3842b19b6d8 100644
--- a/libstdc++-v3/testsuite/experimental/net/timer/waitable/dest.cc
+++ b/libstdc++-v3/testsuite/experimental/net/timer/waitable/dest.cc
@@ -38,7 +38,7 @@ test01()
     timer.async_wait([&ec](std::error_code e) { ec = e; });
   }
   auto n = ctx.run();
-  __builtin_printf("ran %lu\n", n);
+  __builtin_printf("ran %lu\n", long(n));
   VERIFY( n == 1 );
   VERIFY( ec == std::errc::operation_canceled );
 }