Fix Python 2.7 support
diff --git a/asn1crypto/core.py b/asn1crypto/core.py
index 52cab67..0f06f7d 100644
--- a/asn1crypto/core.py
+++ b/asn1crypto/core.py
@@ -137,7 +137,7 @@
     print('%s  Data: 0x%s' % (prefix, binascii.hexlify(self.contents or b'').decode('utf-8')))
 
 
-class Asn1Value():
+class Asn1Value(object):
     """
     The basis of all ASN.1 values
     """