diff --git a/main.go b/main.go
index 5b71f5d..e202f51 100644
--- a/main.go
+++ b/main.go
@@ -22,15 +22,17 @@ import (
 type CertificateMetrics struct {
 	Domain string
 	Port   int
+	ALPN   []string
 
 	ExpiryIn prometheus.Gauge
 	IsValid  prometheus.Gauge
 }
 
-func NewCertificateMetrics(domain string, port int) CertificateMetrics {
+func NewCertificateMetrics(domain string, port int, alpn []string) CertificateMetrics {
 	metrics := CertificateMetrics{
 		Domain: domain,
 		Port:   port,
+		ALPN:   alpn,
 		ExpiryIn: prometheus.NewGauge(
 			prometheus.GaugeOpts{
 				Name:        "cert_status_expiry_in",
@@ -59,8 +61,11 @@ func (c *CertificateMetrics) register(registry *prometheus.Registry) {
 }
 
 func (c *CertificateMetrics) checkTls() {
-	conn, err := tls.Dial("tcp", c.Domain+":"+fmt.Sprint(c.Port), &tls.Config{})
+	conn, err := tls.Dial("tcp", c.Domain+":"+fmt.Sprint(c.Port), &tls.Config{
+		NextProtos: c.ALPN,
+	})
 	if err != nil {
+		log.Debugf("Failed to dial %s:%d@%s using ALPN %v: %v", c.Domain, c.Port, "tcp", c.ALPN, err)
 		c.IsValid.Set(0)
 		return
 	}
@@ -107,9 +112,9 @@ func run(ctx *cli.Context) error {
 	for _, d := range domains {
 		log.Debugf("Parsing '%s'...", d)
 		parts := strings.Split(d, ":")
-		if len(parts) != 2 {
+		if len(parts) != 3 {
 			log.Errorf("Invalid domain format for '%s'", d)
-			return errors.New("Invalid domain format: Expects <domain>:<port>")
+			return errors.New("Invalid domain format: Expects <domain>:<port>:<alpn>")
 		}
 
 		port, err := strconv.Atoi(parts[1])
@@ -119,9 +124,13 @@ func run(ctx *cli.Context) error {
 		}
 
 		// Create the metric, and register it
+		// TODO: Make this prettier
+		alpn := strings.Split(parts[2], ";")
+		log.Debugf("Using ALPNs: %v", alpn)
 		metric := NewCertificateMetrics(
 			parts[0],
 			port,
+			alpn,
 		)
 		metric.register(registry)
 		metrics = append(metrics, metric)