diff --git a/lib/pem.py b/lib/pem.py
index 48e65f5a4..eda65d5fb 100644
--- a/lib/pem.py
+++ b/lib/pem.py
@@ -30,7 +30,7 @@
 
 import binascii
 
-from x509 import ASN1_Node
+from x509 import ASN1_Node, bytestr_to_int, decode_OID
 
 
 def a2b_base64(s):
@@ -173,6 +173,7 @@ def bytesToNumber(s):
 
 
 def _parseASN1PrivateKey(s):
+    s = ASN1_Node(s)
     root = s.root()
     version_node = s.first_child(root)
     version = bytestr_to_int(s.get_value_of_type(version_node, 'INTEGER'))