diff --git a/vendor/github.com/sideshow/apns2/certificate/certificate.go b/vendor/github.com/sideshow/apns2/certificate/certificate.go
index e103db0..cfd78de 100644
--- a/vendor/github.com/sideshow/apns2/certificate/certificate.go
+++ b/vendor/github.com/sideshow/apns2/certificate/certificate.go
@@ -16,17 +16,17 @@ import (
 
 // Possible errors when parsing a certificate.
 var (
-	ErrFailedToDecryptKey           = errors.New("failed to decrypt private key")
-	ErrFailedToParsePKCS1PrivateKey = errors.New("failed to parse PKCS1 private key")
-	ErrFailedToParseCertificate     = errors.New("failed to parse certificate PEM data")
-	ErrNoPrivateKey                 = errors.New("no private key")
-	ErrNoCertificate                = errors.New("no certificate")
+	ErrFailedToDecryptKey       = errors.New("failed to decrypt private key")
+	ErrFailedToParsePrivateKey  = errors.New("failed to parse private key")
+	ErrFailedToParseCertificate = errors.New("failed to parse certificate PEM data")
+	ErrNoPrivateKey             = errors.New("no private key")
+	ErrNoCertificate            = errors.New("no certificate")
 )
 
 // FromP12File loads a PKCS#12 certificate from a local file and returns a
 // tls.Certificate.
 //
-// Use "" as the password argument if the pem certificate is not password
+// Use "" as the password argument if the PKCS#12 certificate is not password
 // protected.
 func FromP12File(filename string, password string) (tls.Certificate, error) {
 	p12bytes, err := ioutil.ReadFile(filename)
@@ -120,9 +120,14 @@ func unencryptPrivateKey(block *pem.Block, password string) (crypto.PrivateKey,
 }
 
 func parsePrivateKey(bytes []byte) (crypto.PrivateKey, error) {
+	var key crypto.PrivateKey
 	key, err := x509.ParsePKCS1PrivateKey(bytes)
-	if err != nil {
-		return nil, ErrFailedToParsePKCS1PrivateKey
+	if err == nil {
+		return key, nil
 	}
-	return key, nil
+	key, err = x509.ParsePKCS8PrivateKey(bytes)
+	if err == nil {
+		return key, nil
+	}
+	return nil, ErrFailedToParsePrivateKey
 }
diff --git a/vendor/vendor.json b/vendor/vendor.json
index 0803ed4..3a8a606 100644
--- a/vendor/vendor.json
+++ b/vendor/vendor.json
@@ -451,16 +451,16 @@
 			"versionExact": "v0.13"
 		},
 		{
-			"checksumSHA1": "c3x81Xq+gIn5JBgs1eCTVeRwDDo=",
+			"checksumSHA1": "EHOwwdWPJGt1vNVeJxyRDRHBhl8=",
 			"path": "github.com/sideshow/apns2/certificate",
-			"revision": "c23f4b07d9e47aa490ff76001001decc688243f8",
-			"revisionTime": "2017-01-05T14:10:18Z"
+			"revision": "c6554aff77e6e5580dec977c8c33cc238f329ab0",
+			"revisionTime": "2018-04-13T21:53:35Z"
 		},
 		{
 			"checksumSHA1": "9Lxz0w+q8pqp/Do/kNa8hLoQeY0=",
 			"path": "github.com/sideshow/apns2/payload",
-			"revision": "c23f4b07d9e47aa490ff76001001decc688243f8",
-			"revisionTime": "2017-01-05T14:10:18Z"
+			"revision": "c6554aff77e6e5580dec977c8c33cc238f329ab0",
+			"revisionTime": "2018-04-13T21:53:35Z"
 		},
 		{
 			"checksumSHA1": "nkQ/1JoIY4jh8XlI8LClfFVux9U=",