diff --git a/tests/dns/byaddr_test.c b/tests/dns/byaddr_test.c
index 2cb3ee9c53..fb15880c2a 100644
--- a/tests/dns/byaddr_test.c
+++ b/tests/dns/byaddr_test.c
@@ -13,6 +13,7 @@
 
 #include <sched.h> /* IWYU pragma: keep */
 #include <setjmp.h>
+#include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>