Index: src/libspf2/spf_dns_resolv.c
--- src/libspf2/spf_dns_resolv.c.orig
+++ src/libspf2/spf_dns_resolv.c
@@ -591,7 +591,10 @@ SPF_dns_resolv_free(SPF_dns_server_t *spf_dns_server)
 	SPF_ASSERT_NOTNULL(spf_dns_server);
 
 #if ! HAVE_DECL_RES_NINIT
+#  ifndef __OpenBSD__
+	/* OpenBSD's libc resolver provides res_init() but not res_close(). */
 	res_close();
+#  endif
 #endif
 
 	free(spf_dns_server);
