diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index bae5a2bd0a..a91a5d52ff 100644
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -4983,7 +4983,6 @@ fctx_create(dns_resolver_t *res, const dns_name_t *name, dns_rdatatype_t type,
 	isc_interval_t interval;
 	unsigned int findoptions = 0;
 	char buf[DNS_NAME_FORMATSIZE + DNS_RDATATYPE_FORMATSIZE + 1];
-	char typebuf[DNS_RDATATYPE_FORMATSIZE];
 	isc_mem_t *mctx;
 	size_t p;
 	bool try_stale;
@@ -5012,9 +5011,9 @@ fctx_create(dns_resolver_t *res, const dns_name_t *name, dns_rdatatype_t type,
 	 * "name/type".
 	 */
 	dns_name_format(name, buf, sizeof(buf));
-	dns_rdatatype_format(type, typebuf, sizeof(typebuf));
 	p = strlcat(buf, "/", sizeof(buf));
-	strlcat(buf + p, typebuf, sizeof(buf));
+	INSIST(p + DNS_RDATATYPE_FORMATSIZE < sizeof(buf));
+	dns_rdatatype_format(type, buf + p, sizeof(buf) - p);
 	fctx->info = isc_mem_strdup(mctx, buf);
 
 	FCTXTRACE("create");