diff --git a/lib/common/certificate/certificate.go b/lib/common/certificate/certificate.go
index 4865276..1d27569 100644
--- a/lib/common/certificate/certificate.go
+++ b/lib/common/certificate/certificate.go
@@ -252,7 +252,7 @@ func NewCertificateWithType(certType uint8, payload []byte) (*Certificate, error
 
 func GetSignatureTypeFromCertificate(cert Certificate) (int, error) {
 	if cert.Type() != CERT_KEY {
-		return 0, fmt.Errorf("unexpected certificate type: %d", cert.Type)
+		return 0, fmt.Errorf("unexpected certificate type: %d", cert.Type())
 	}
 	if len(cert.payload) < 2 {
 		return 0, fmt.Errorf("certificate payload too short to contain signature type")