diff --git a/bin/tests/wire_test.c b/bin/tests/wire_test.c
index 772382849e..21c960ebed 100644
--- a/bin/tests/wire_test.c
+++ b/bin/tests/wire_test.c
@@ -286,7 +286,7 @@ process_message(isc_buffer_t *source) {
 	}
 
 	if (dorender) {
-		unsigned char b2[64 * 1024];
+		unsigned char b2[65535];
 		isc_buffer_t buffer;
 		dns_compress_t cctx;
 
diff --git a/tests/libtest/ns.c b/tests/libtest/ns.c
index 67be306d46..6f66b00a3c 100644
--- a/tests/libtest/ns.c
+++ b/tests/libtest/ns.c
@@ -250,7 +250,7 @@ attach_query_msg_to_client(ns_client_t *client, const char *qnamestr,
 			   dns_rdatatype_t qtype, unsigned int qflags) {
 	dns_rdataset_t *qrdataset = NULL;
 	dns_message_t *message = NULL;
-	unsigned char query[65536];
+	unsigned char query[65535];
 	dns_name_t *qname = NULL;
 	isc_buffer_t querybuf;
 	dns_compress_t cctx;