diff --git a/internal/cert/root_ca_test.go b/internal/cert/root_ca_test.go
index 7de3e1d..f252ef5 100644
--- a/internal/cert/root_ca_test.go
+++ b/internal/cert/root_ca_test.go
@@ -83,6 +83,12 @@ func Test_newRootCA(t *testing.T) {
 	require.Greater(t, len(keyPEM), 0)
 }
 
+func Test_newRootCAError(t *testing.T) {
+	_, _, err := newRootCA(&ca.CaConfig{})
+
+	require.Error(t, err)
+}
+
 func Test_parseCertificate(t *testing.T) {
 	caPEM, _, err := newRootCA(&rootTestConfig)
 	require.NoError(t, err)
@@ -126,3 +132,12 @@ func Test_rootCA_WithClientCert(t *testing.T) {
 	require.NotNil(t, clientSrv.PEM())
 	require.Greater(t, len(clientSrv.PEM()), 0)
 }
+
+func Test_rootCA_WithClientCertEror(t *testing.T) {
+	rootCert := rootCA{
+		caPEM: nil,
+	}
+
+	_, err := rootCert.WithClientCert(&clientTestConfig)
+	require.Error(t, err)
+}
diff --git a/pkg/client/client.go b/pkg/client/client.go
index ebae188..8725f65 100644
--- a/pkg/client/client.go
+++ b/pkg/client/client.go
@@ -34,21 +34,3 @@ var (
 	extKeyUsage  = []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth, x509.ExtKeyUsageServerAuth}
 	keyUsage     = x509.KeyUsageDigitalSignature
 )
-
-func NewDefaultConfig() *ClientCertConfig {
-	return &ClientCertConfig{
-		Serial: big.NewInt(12321),
-		Subject: Subject{
-			Organization:  "",
-			Country:       "",
-			Province:      "",
-			Locality:      "",
-			StreetAddress: "",
-			PostalCode:    "",
-		},
-		Duration:     time.Duration(time.Hour * 24 * 365),
-		SubjectKeyId: subjectKeyId,
-		ExtKeyUsage:  extKeyUsage,
-		KeyUsage:     keyUsage,
-	}
-}