diff --git a/m4/cares-functions.m4 b/m4/cares-functions.m4
index 0ba03247..8f3fa72e 100644
--- a/m4/cares-functions.m4
+++ b/m4/cares-functions.m4
@@ -200,7 +200,7 @@ dnl shell variable cares_disallow_getservbyport_r, then
 dnl HAVE_GETSERVBYPORT_R will be defined.
 
 AC_DEFUN([CARES_CHECK_FUNC_GETSERVBYPORT_R], [
-  AC_REQUIRE([CARES_INCLUDES_SYS_UIO])dnl
+  AC_REQUIRE([CARES_INCLUDES_NETDB])dnl
   #
   tst_links_getservbyport_r="unknown"
   tst_proto_getservbyport_r="unknown"