diff --git a/wolfssl/__init__.py b/wolfssl/__init__.py
index fbb28f0..e236fa4 100644
--- a/wolfssl/__init__.py
+++ b/wolfssl/__init__.py
@@ -56,9 +56,11 @@
 )
 
 CERT_NONE = 0
-CERT_REQUIRED = 1
+CERT_OPTIONAL = 1
+_CERT_VERIFY_FAIL_IF_NO_PEER_CERT = 2
+CERT_REQUIRED = CERT_OPTIONAL | _CERT_VERIFY_FAIL_IF_NO_PEER_CERT
 
-_VERIFY_MODE_LIST = [CERT_NONE, CERT_REQUIRED]
+_VERIFY_MODE_LIST = [CERT_NONE, CERT_OPTIONAL, CERT_REQUIRED]
 
 _SSL_SUCCESS = 1
 _SSL_FILETYPE_PEM = 1