diff --git a/bin/dnssec/dnssec-signzone.c b/bin/dnssec/dnssec-signzone.c
index 8461134e67..cfb8f5141e 100644
--- a/bin/dnssec/dnssec-signzone.c
+++ b/bin/dnssec/dnssec-signzone.c
@@ -2034,7 +2034,7 @@ addnsec3(dns_name_t *name, dns_dbnode_t *node, const unsigned char *salt,
 	dns_fixedname_init(&hashname);
 	dns_rdataset_init(&rdataset);
 
-	dns_name_downcase(name, name, NULL);
+	dns_name_downcase(name, name);
 	result = dns_nsec3_hashname(&hashname, hash, &hash_len, name, gorigin,
 				    dns_hash_sha1, iterations, salt, salt_len);
 	check_result(result, "addnsec3: dns_nsec3_hashname()");
@@ -2402,7 +2402,7 @@ nsec3ify(unsigned int hashalg, dns_iterations_t iterations,
 			fatal("iterating through the database failed: %s",
 			      isc_result_totext(result));
 		}
-		dns_name_downcase(name, name, NULL);
+		dns_name_downcase(name, name);
 		hashlist_add_dns_name(hashlist, name, hashalg, iterations, salt,
 				      salt_len, false);
 		dns_db_detachnode(gdb, &node);
@@ -2412,7 +2412,7 @@ nsec3ify(unsigned int hashalg, dns_iterations_t iterations,
 		 * node for another <name,nextname> span so we don't add
 		 * it here.  Empty labels on nextname are within the span.
 		 */
-		dns_name_downcase(nextname, nextname, NULL);
+		dns_name_downcase(nextname, nextname);
 		dns_name_fullcompare(name, nextname, &order, &nlabels);
 		addnowildcardhash(hashlist, name, hashalg, iterations, salt,
 				  salt_len);
diff --git a/bin/named/server.c b/bin/named/server.c
index cb9e390cc6..9f6d021bbf 100644
--- a/bin/named/server.c
+++ b/bin/named/server.c
@@ -12541,7 +12541,7 @@ nzd_setkey(MDB_val *key, dns_name_t *name, char *namebuf, size_t buflen) {
 	dns_fixedname_t fixed;
 
 	dns_fixedname_init(&fixed);
-	dns_name_downcase(name, dns_fixedname_name(&fixed), NULL);
+	dns_name_downcase(name, dns_fixedname_name(&fixed));
 	dns_name_format(dns_fixedname_name(&fixed), namebuf, buflen);
 
 	key->mv_data = namebuf;
diff --git a/bin/tools/nsec3hash.c b/bin/tools/nsec3hash.c
index 0ddc6fa067..c0f62375d8 100644
--- a/bin/tools/nsec3hash.c
+++ b/bin/tools/nsec3hash.c
@@ -125,7 +125,7 @@ nsec3hash(nsec3printer *nsec3print, const char *algostr, const char *flagstr,
 	result = dns_name_fromtext(name, &buffer, dns_rootname, 0, NULL);
 	check_result(result, "dns_name_fromtext() failed");
 
-	dns_name_downcase(name, name, NULL);
+	dns_name_downcase(name, name);
 	length = isc_iterated_hash(hash, hash_alg, iterations, salt,
 				   salt_length, name->ndata, name->length);
 	if (length == 0) {
diff --git a/lib/dns/dnssec.c b/lib/dns/dnssec.c
index 8746df9843..cda1115ded 100644
--- a/lib/dns/dnssec.c
+++ b/lib/dns/dnssec.c
@@ -167,8 +167,8 @@ digest_sig(dst_context_t *ctx, bool downcase, dns_rdata_t *sigrdata,
 		dns_fixedname_init(&fname);
 
 		RUNTIME_CHECK(dns_name_downcase(&rrsig->signer,
-						dns_fixedname_name(&fname),
-						NULL) == ISC_R_SUCCESS);
+						dns_fixedname_name(&fname)) ==
+			      ISC_R_SUCCESS);
 		dns_name_toregion(dns_fixedname_name(&fname), &r);
 	} else {
 		dns_name_toregion(&rrsig->signer, &r);
@@ -231,8 +231,8 @@ dns_dnssec_sign(const dns_name_t *name, dns_rdataset_t *set, dst_key_t *key,
 	dns_name_init(&sig.signer);
 	dns_fixedname_init(&fsigner);
 	RUNTIME_CHECK(dns_name_downcase(dst_key_name(key),
-					dns_fixedname_name(&fsigner),
-					NULL) == ISC_R_SUCCESS);
+					dns_fixedname_name(&fsigner)) ==
+		      ISC_R_SUCCESS);
 	dns_name_clone(dns_fixedname_name(&fsigner), &sig.signer);
 
 	sig.covered = set->type;
@@ -280,8 +280,8 @@ dns_dnssec_sign(const dns_name_t *name, dns_rdataset_t *set, dst_key_t *key,
 	}
 
 	dns_fixedname_init(&fnewname);
-	RUNTIME_CHECK(dns_name_downcase(name, dns_fixedname_name(&fnewname),
-					NULL) == ISC_R_SUCCESS);
+	RUNTIME_CHECK(dns_name_downcase(name, dns_fixedname_name(&fnewname)) ==
+		      ISC_R_SUCCESS);
 	dns_name_toregion(dns_fixedname_name(&fnewname), &r);
 
 	/*
@@ -479,8 +479,8 @@ again:
 	 */
 	dns_fixedname_init(&fnewname);
 	labels = dns_name_countlabels(name) - 1;
-	RUNTIME_CHECK(dns_name_downcase(name, dns_fixedname_name(&fnewname),
-					NULL) == ISC_R_SUCCESS);
+	RUNTIME_CHECK(dns_name_downcase(name, dns_fixedname_name(&fnewname)) ==
+		      ISC_R_SUCCESS);
 	if (labels - sig.labels > 0) {
 		dns_name_split(dns_fixedname_name(&fnewname), sig.labels + 1,
 			       NULL, dns_fixedname_name(&fnewname));
diff --git a/lib/dns/ds.c b/lib/dns/ds.c
index 07879018b7..c56691bf19 100644
--- a/lib/dns/ds.c
+++ b/lib/dns/ds.c
@@ -67,7 +67,7 @@ dns_ds_fromkeyrdata(const dns_name_t *owner, dns_rdata_t *key,
 	}
 
 	name = dns_fixedname_initname(&fname);
-	(void)dns_name_downcase(owner, name, NULL);
+	(void)dns_name_downcase(owner, name);
 
 	md = isc_md_new();
 
diff --git a/lib/dns/include/dns/name.h b/lib/dns/include/dns/name.h
index 4876ea6c1d..24340b2e4b 100644
--- a/lib/dns/include/dns/name.h
+++ b/lib/dns/include/dns/name.h
@@ -937,8 +937,7 @@ dns_name_tofilenametext(const dns_name_t *name, bool omit_final_dot,
  */
 
 isc_result_t
-dns_name_downcase(const dns_name_t *source, dns_name_t *name,
-		  isc_buffer_t *target);
+dns_name_downcase(const dns_name_t *source, dns_name_t *name);
 /*%<
  * Downcase 'source'.
  *
@@ -949,9 +948,7 @@ dns_name_downcase(const dns_name_t *source, dns_name_t *name,
  *\li	If source == name, then
  *		'source' must not be read-only
  *
- *\li	Otherwise,
- *		'target' is a valid buffer or 'target' is NULL and
- *		'name' has a dedicated buffer.
+ *\li	'name' has a dedicated buffer.
  *
  * Returns:
  *\li	#ISC_R_SUCCESS
diff --git a/lib/dns/name.c b/lib/dns/name.c
index f05f8a97de..64ba287804 100644
--- a/lib/dns/name.c
+++ b/lib/dns/name.c
@@ -1229,11 +1229,7 @@ dns_name_tofilenametext(const dns_name_t *name, bool omit_final_dot,
 }
 
 isc_result_t
-dns_name_downcase(const dns_name_t *source, dns_name_t *name,
-		  isc_buffer_t *target) {
-	unsigned char *ndata;
-	isc_buffer_t buffer;
-
+dns_name_downcase(const dns_name_t *source, dns_name_t *name) {
 	/*
 	 * Downcase 'source'.
 	 */
@@ -1243,37 +1239,24 @@ dns_name_downcase(const dns_name_t *source, dns_name_t *name,
 
 	if (source == name) {
 		REQUIRE(!name->attributes.readonly);
-		isc_buffer_init(&buffer, source->ndata, source->length);
-		target = &buffer;
-		ndata = source->ndata;
-	} else {
-		REQUIRE(DNS_NAME_BINDABLE(name));
-		REQUIRE((target != NULL && ISC_BUFFER_VALID(target)) ||
-			(target == NULL && ISC_BUFFER_VALID(name->buffer)));
-		if (target == NULL) {
-			if (source->length > name->buffer->length) {
-				return ISC_R_NOSPACE;
-			}
-			target = name->buffer;
-			isc_buffer_clear(name->buffer);
-		} else if (source->length > target->length - target->used) {
-			return ISC_R_NOSPACE;
-		}
-		ndata = (unsigned char *)target->base + target->used;
-		name->ndata = ndata;
+		isc_ascii_lowercopy(name->ndata, source->ndata, source->length);
+		return ISC_R_SUCCESS;
 	}
 
+	REQUIRE(DNS_NAME_BINDABLE(name));
+	REQUIRE(ISC_BUFFER_VALID(name->buffer));
+
+	isc_buffer_clear(name->buffer);
+	name->ndata = (uint8_t *)name->buffer->base + name->buffer->used;
+
 	/* label lengths are < 64 so tolower() does not affect them */
-	isc_ascii_lowercopy(ndata, source->ndata, source->length);
+	isc_ascii_lowercopy(name->ndata, source->ndata, source->length);
 
-	if (source != name) {
-		name->length = source->length;
-		name->attributes = (struct dns_name_attrs){
-			.absolute = source->attributes.absolute
-		};
-	}
-
-	isc_buffer_add(target, name->length);
+	name->length = source->length;
+	name->attributes = (struct dns_name_attrs){
+		.absolute = source->attributes.absolute
+	};
+	isc_buffer_add(name->buffer, name->length);
 
 	return ISC_R_SUCCESS;
 }
@@ -1696,12 +1679,6 @@ dns_name_size(const dns_name_t *name) {
 
 isc_result_t
 dns_name_digest(const dns_name_t *name, dns_digestfunc_t digest, void *arg) {
-	dns_name_t downname;
-	unsigned char data[256];
-	isc_buffer_t buffer;
-	isc_result_t result;
-	isc_region_t r;
-
 	/*
 	 * Send 'name' in DNSSEC canonical form to 'digest'.
 	 */
@@ -1709,17 +1686,13 @@ dns_name_digest(const dns_name_t *name, dns_digestfunc_t digest, void *arg) {
 	REQUIRE(DNS_NAME_VALID(name));
 	REQUIRE(digest != NULL);
 
-	dns_name_init(&downname);
-
-	isc_buffer_init(&buffer, data, sizeof(data));
-
-	result = dns_name_downcase(name, &downname, &buffer);
-	if (result != ISC_R_SUCCESS) {
-		return result;
-	}
-
-	isc_buffer_usedregion(&buffer, &r);
+	unsigned char ndata[DNS_NAME_MAXWIRE];
+	isc_ascii_lowercopy(ndata, name->ndata, name->length);
 
+	isc_region_t r = {
+		.base = ndata,
+		.length = name->length,
+	};
 	return (digest)(arg, &r);
 }
 
diff --git a/lib/dns/nsec3.c b/lib/dns/nsec3.c
index 3c02f0d664..d0d3eadda7 100644
--- a/lib/dns/nsec3.c
+++ b/lib/dns/nsec3.c
@@ -261,7 +261,7 @@ dns_nsec3_hashname(dns_fixedname_t *result,
 	memset(rethash, 0, NSEC3_MAX_HASH_LENGTH);
 
 	downcased = dns_fixedname_initname(&fixed);
-	dns_name_downcase(name, downcased, NULL);
+	dns_name_downcase(name, downcased);
 
 	/* hash the node name */
 	len = isc_iterated_hash(rethash, hashalg, iterations, salt,
@@ -2022,7 +2022,7 @@ dns_nsec3_noexistnodata(dns_rdatatype_t type, const dns_name_t *name,
 	 * Prepare to compute all the hashes.
 	 */
 	qname = dns_fixedname_initname(&qfixed);
-	dns_name_downcase(name, qname, NULL);
+	dns_name_downcase(name, qname);
 	qlabels = dns_name_countlabels(qname);
 	first = true;
 
diff --git a/lib/dns/rpz.c b/lib/dns/rpz.c
index 331fe83840..130d833f3f 100644
--- a/lib/dns/rpz.c
+++ b/lib/dns/rpz.c
@@ -1797,7 +1797,7 @@ update_nodes(dns_rpz_zone_t *rpz, isc_ht_t *newnodes) {
 			goto next;
 		}
 
-		dns_name_downcase(name, name, NULL);
+		dns_name_downcase(name, name);
 
 		/* Add entry to the new nodes table */
 		result = isc_ht_add(newnodes, name->ndata, name->length, rpz);
diff --git a/lib/dns/tsig.c b/lib/dns/tsig.c
index f365ae93ee..828a4addf1 100644
--- a/lib/dns/tsig.c
+++ b/lib/dns/tsig.c
@@ -235,7 +235,7 @@ dns_tsigkey_createfromkey(const dns_name_t *name, dst_algorithm_t algorithm,
 
 	tkey->name = dns_fixedname_initname(&tkey->fn);
 	dns_name_copy(name, tkey->name);
-	(void)dns_name_downcase(tkey->name, tkey->name, NULL);
+	(void)dns_name_downcase(tkey->name, tkey->name);
 
 	if (algorithm != DST_ALG_UNKNOWN) {
 		if (dstkey != NULL && dst_key_alg(dstkey) != algorithm) {
diff --git a/lib/dns/validator.c b/lib/dns/validator.c
index b39fa34c18..fd73251976 100644
--- a/lib/dns/validator.c
+++ b/lib/dns/validator.c
@@ -300,7 +300,7 @@ trynsec3:
 	found = false;
 	dns_name_init(&nsec3name);
 	dns_fixedname_init(&fixed);
-	dns_name_downcase(name, dns_fixedname_name(&fixed), NULL);
+	dns_name_downcase(name, dns_fixedname_name(&fixed));
 	name = dns_fixedname_name(&fixed);
 	for (result = dns_rdataset_first(rdataset); result == ISC_R_SUCCESS;
 	     result = dns_rdataset_next(rdataset))
diff --git a/lib/dns/zone.c b/lib/dns/zone.c
index 119de7ed68..98690078b2 100644
--- a/lib/dns/zone.c
+++ b/lib/dns/zone.c
@@ -19093,7 +19093,7 @@ zonemgr_keymgmt_add(dns_zonemgr_t *zmgr, dns_zone_t *zone,
 	REQUIRE(added != NULL && *added == NULL);
 
 	name = dns_fixedname_initname(&fname);
-	dns_name_downcase(&zone->origin, name, NULL);
+	dns_name_downcase(&zone->origin, name);
 
 	RWLOCK(&mgmt->lock, isc_rwlocktype_write);