diff --git a/Build/worker/build-reject-domainset-worker.js b/Build/worker/build-reject-domainset-worker.js
index e3bba42f..b9032676 100644
--- a/Build/worker/build-reject-domainset-worker.js
+++ b/Build/worker/build-reject-domainset-worker.js
@@ -66,7 +66,7 @@ module.exports = ({ chunk }) => {
 
 // duckdns.org domain will not overlap and doesn't need dedupe
 function canExcludeFromDedupe(domain) {
-  if (domain.endsWith('.duckdns.org')) {
+  if (domain.length === 23 && domain.endsWith('.duckdns.org')) {
     return true;
   }
   return false;
diff --git a/List/non_ip/reject.conf b/List/non_ip/reject.conf
index 39091720..a2f270a2 100644
--- a/List/non_ip/reject.conf
+++ b/List/non_ip/reject.conf
@@ -35,6 +35,7 @@ DOMAIN-KEYWORD,49329d48d6c.
 DOMAIN-KEYWORD,vsvevvcca
 DOMAIN-KEYWORD,envci.
 DOMAIN-KEYWORD,aarsenvs.
+DOMAIN-SUFFIX,duckdns.org
 
 # --- End of Blacklist Section