diff --git a/internal/dnsforward/beforerequest_internal_test.go b/internal/dnsforward/beforerequest_internal_test.go
index 409838c2..4f2107e7 100644
--- a/internal/dnsforward/beforerequest_internal_test.go
+++ b/internal/dnsforward/beforerequest_internal_test.go
@@ -42,6 +42,17 @@ func TestServer_HandleBefore(t *testing.T) {
 		blockedHosts:      []string{},
 		wantRCode:         dns.RcodeSuccess,
 		wantRCodeUDP:      dns.RcodeSuccess,
+	}, {
+		want:              assert.Empty,
+		clientSrvName:     "%" + "." + tlsServerName,
+		name:              "invalid_client_id",
+		host:              testFQDN,
+		wantErrMsgUDP:     "",
+		allowedClients:    []string{},
+		disallowedClients: []string{},
+		blockedHosts:      []string{},
+		wantRCode:         dns.RcodeServerFailure,
+		wantRCodeUDP:      dns.RcodeSuccess,
 	}, {
 		want:              assert.NotEmpty,
 		clientSrvName:     clientID + "." + tlsServerName,