diff --git a/bin/named/server.c b/bin/named/server.c
index d28926914e..7c2499ea2a 100644
--- a/bin/named/server.c
+++ b/bin/named/server.c
@@ -14921,7 +14921,12 @@ named_server_signing(named_server_t *server, isc_lex_t *lex,
 		     result = dns_rdataset_next(&privset))
 		{
 			dns_rdata_t priv = DNS_RDATA_INIT;
-			char output[BUFSIZ];
+			/*
+			 * In theory, the output buffer could hold a full RDATA
+			 * record which is 16-bit and then some text around
+			 * it
+			 */
+			char output[UINT16_MAX + BUFSIZ];
 			isc_buffer_t buf;
 
 			dns_rdataset_current(&privset, &priv);
diff --git a/bin/tests/system/feature-test.c b/bin/tests/system/feature-test.c
index 30e6e14575..3435c91e07 100644
--- a/bin/tests/system/feature-test.c
+++ b/bin/tests/system/feature-test.c
@@ -11,6 +11,7 @@
  * information regarding copyright ownership.
  */
 
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -22,14 +23,6 @@
 
 #include <dns/edns.h>
 
-#ifndef MAXHOSTNAMELEN
-#ifdef HOST_NAME_MAX
-#define MAXHOSTNAMELEN HOST_NAME_MAX
-#else /* ifdef HOST_NAME_MAX */
-#define MAXHOSTNAMELEN 256
-#endif /* ifdef HOST_NAME_MAX */
-#endif /* ifndef MAXHOSTNAMELEN */
-
 static void
 usage(void) {
 	fprintf(stderr, "usage: feature-test <arg>\n");
@@ -91,7 +84,7 @@ main(int argc, char **argv) {
 	}
 
 	if (strcmp(argv[1], "--gethostname") == 0) {
-		char hostname[MAXHOSTNAMELEN];
+		char hostname[_POSIX_HOST_NAME_MAX + 1];
 		int n;
 
 		n = gethostname(hostname, sizeof(hostname));
diff --git a/lib/dns/adb.c b/lib/dns/adb.c
index b97f3e6390..3ff149a774 100644
--- a/lib/dns/adb.c
+++ b/lib/dns/adb.c
@@ -3010,7 +3010,7 @@ dns_adb_dumpquota(dns_adb_t *adb, isc_buffer_t **buf) {
 		     entry = ISC_LIST_NEXT(entry, plink))
 		{
 			char addrbuf[ISC_NETADDR_FORMATSIZE];
-			char text[BUFSIZ];
+			char text[ISC_NETADDR_FORMATSIZE + BUFSIZ];
 			isc_netaddr_t netaddr;
 
 			if (entry->atr == 0.0 && entry->quota == adb->quota) {
diff --git a/lib/dns/private.c b/lib/dns/private.c
index 58deda095a..cbf947f8cc 100644
--- a/lib/dns/private.c
+++ b/lib/dns/private.c
@@ -383,7 +383,8 @@ dns_private_totext(dns_rdata_t *private, isc_buffer_t *buf) {
 	} else if (private->length == 5) {
 		unsigned char alg = private->data[0];
 		dns_keytag_t keyid = (private->data[2] | private->data[1] << 8);
-		char keybuf[BUFSIZ], algbuf[DNS_SECALG_FORMATSIZE];
+		char keybuf[DNS_SECALG_FORMATSIZE + BUFSIZ],
+			algbuf[DNS_SECALG_FORMATSIZE];
 		bool del = private->data[3];
 		bool complete = private->data[4];
 
diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index ddc0ed5041..7fa7040aa2 100644
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -11538,7 +11538,8 @@ dns_resolver_dumpquota(dns_resolver_t *res, isc_buffer_t **buf) {
 		for (fctxcount_t *fc = ISC_LIST_HEAD(bucket->list); fc != NULL;
 		     fc = ISC_LIST_NEXT(fc, link))
 		{
-			char nb[DNS_NAME_FORMATSIZE], text[BUFSIZ];
+			char nb[DNS_NAME_FORMATSIZE],
+				text[DNS_NAME_FORMATSIZE + BUFSIZ];
 
 			if (fc->count < spill) {
 				continue;
diff --git a/lib/ns/client.c b/lib/ns/client.c
index 836cedc8e1..436cc19a89 100644
--- a/lib/ns/client.c
+++ b/lib/ns/client.c
@@ -12,6 +12,7 @@
  */
 
 #include <inttypes.h>
+#include <limits.h>
 #include <stdbool.h>
 
 #include <isc/aes.h>
@@ -955,7 +956,7 @@ isc_result_t
 ns_client_addopt(ns_client_t *client, dns_message_t *message,
 		 dns_rdataset_t **opt) {
 	unsigned char ecs[ECS_SIZE];
-	char nsid[BUFSIZ], *nsidp = NULL;
+	char nsid[_POSIX_HOST_NAME_MAX + 1], *nsidp = NULL;
 	unsigned char cookie[COOKIE_SIZE];
 	isc_result_t result;
 	dns_view_t *view = NULL;