diff --git a/internal/clis/hmpki/generate_ca.go b/internal/clis/hmpki/generate_ca.go
index ae631f9..4d8192f 100644
--- a/internal/clis/hmpki/generate_ca.go
+++ b/internal/clis/hmpki/generate_ca.go
@@ -5,9 +5,6 @@ import (
 	"crypto/x509"
 	"crypto/x509/pkix"
 	"encoding/pem"
-	"errors"
-	"math"
-	"math/big"
 	"path"
 	"time"
 
@@ -32,17 +29,11 @@ var generateCACmd = &cobra.Command{
 	Short: "Generate a Certificate Authority",
 	RunE: func(cmd *cobra.Command, args []string) error {
 		// Private key for the ca.
-		key := pki.GenerateKey()
+		key := pki.NewKey()
 
-		// Cryptographically random 64bit number as the serial.
-		sn, err := rand.Int(rand.Reader, big.NewInt(math.MaxInt64))
-		if err != nil {
-			return errors.New("Could not generate a ca serial number")
-		}
 		caTmpl := &x509.Certificate{
-			SerialNumber: sn,
+			SerialNumber: pki.NewCertSerialNumber(),
 			Subject: pkix.Name{
-				// TODO: Accept common name as a flag.
 				CommonName: CommonName,
 			},
 			// Valid starting now and for 10 years.