diff --git a/protocol/tailscale/dns_transport.go b/protocol/tailscale/dns_transport.go
index 42452227..08876ea9 100644
--- a/protocol/tailscale/dns_transport.go
+++ b/protocol/tailscale/dns_transport.go
@@ -267,7 +267,7 @@ func (t *DNSTransport) PreferredDomain(domain string) bool {
 		return true
 	}
 	for suffix := range routes {
-		if strings.HasSuffix(domain, suffix) {
+		if mDNS.IsSubDomain(suffix, domain) {
 			return true
 		}
 	}
diff --git a/service/resolved/transport.go b/service/resolved/transport.go
index b00f31a3..c918870a 100644
--- a/service/resolved/transport.go
+++ b/service/resolved/transport.go
@@ -201,7 +201,7 @@ func (t *Transport) PreferredDomain(domain string) bool {
 			if linkDomain.Domain == "." {
 				continue
 			}
-			if strings.HasSuffix(domain, linkDomain.Domain) {
+			if mDNS.IsSubDomain(linkDomain.Domain, domain) {
 				return true
 			}
 		}