diff --git a/lib/interface.py b/lib/interface.py
index 7531ecf9..b0843c40 100644
--- a/lib/interface.py
+++ b/lib/interface.py
@@ -201,8 +201,7 @@ class TcpInterface(threading.Thread):
                     with open(cert_path) as f:
                         cert = f.read()
                     try:
-                        x = x509.X509()
-                        x.parseBinary(cert)
+                        x = x509.X509(cert)
                     except:
                         traceback.print_exc(file=sys.stderr)
                         self.print_error("wrong certificate")
@@ -343,8 +342,7 @@ def check_host_name(peercert, name):
 
 def check_cert(host, cert):
     try:
-        x = x509.X509()
-        x.parseBinary(cert)
+        x = x509.X509(cert)
     except:
         traceback.print_exc(file=sys.stdout)
         return
diff --git a/lib/paymentrequest.py b/lib/paymentrequest.py
index 745e3af5..f2dbfe29 100644
--- a/lib/paymentrequest.py
+++ b/lib/paymentrequest.py
@@ -283,8 +283,7 @@ def verify_cert_chain(chain):
     cert_num = len(chain)
     x509_chain = []
     for i in range(cert_num):
-        x = x509.X509()
-        x.parseBinary(bytearray(chain[i]))
+        x = x509.X509(bytearray(chain[i]))
         x509_chain.append(x)
         if i == 0:
             x.check_date()
diff --git a/lib/x509.py b/lib/x509.py
index 61c22ea1..3f722a16 100644
--- a/lib/x509.py
+++ b/lib/x509.py
@@ -49,7 +49,7 @@ class CertificateError(Exception):
 
 class X509(object):
 
-    def parseBinary(self, b):
+    def __init__(self, b):
 
         self.bytes = bytearray(b)
 
@@ -178,9 +178,8 @@ def load_certificates(ca_path):
         s = f.read()
     bList = pem.dePemList(s, "CERTIFICATE")
     for b in bList:
-        x = X509()
         try:
-            x.parseBinary(b)
+            x = X509(b)
             x.check_date()
         except BaseException as e:
             util.print_error("cert error:", e)