diff --git a/tls/certificate.go b/tls/certificate.go
index 09a69bb57..16bf776c1 100644
--- a/tls/certificate.go
+++ b/tls/certificate.go
@@ -144,7 +144,12 @@ func (c *Certificate) AppendCertificates(certs map[string]*DomainsCertificates,
 	certKey := parsedCert.Subject.CommonName
 	if parsedCert.DNSNames != nil {
 		sort.Strings(parsedCert.DNSNames)
-		certKey += fmt.Sprintf("%s,%s", parsedCert.Subject.CommonName, strings.Join(parsedCert.DNSNames, ","))
+		for _, dnsName := range parsedCert.DNSNames {
+			if dnsName != parsedCert.Subject.CommonName {
+				certKey += fmt.Sprintf(",%s", dnsName)
+			}
+		}
+
 	}
 
 	certExists := false