diff --git a/tests/unit/test-coroutine.c b/tests/unit/test-coroutine.c
index aa77a3bcb3..e16b80c245 100644
--- a/tests/unit/test-coroutine.c
+++ b/tests/unit/test-coroutine.c
@@ -610,7 +610,7 @@ static void perf_baseline(void)
     g_test_message("Function call %u iterations: %f s", maxcycles, duration);
 }
 
-static __attribute__((noinline)) void perf_cost_func(void *opaque)
+static __attribute__((noinline)) void coroutine_fn perf_cost_func(void *opaque)
 {
     qemu_coroutine_yield();
 }