diff --git a/WinHttpConstants.au3 b/WinHttpConstants.au3
index 891e86d..8b9cfa5 100644
--- a/WinHttpConstants.au3
+++ b/WinHttpConstants.au3
@@ -171,6 +171,8 @@ Global Const $WINHTTP_DISABLE_SPN_SERVER_PORT = 0x00000000
 Global Const $WINHTTP_ENABLE_SPN_SERVER_PORT = 0x00000001
 Global Const $WINHTTP_OPTION_SPN_MASK = $WINHTTP_ENABLE_SPN_SERVER_PORT
 
+Global Const $WINHTTP_NO_CLIENT_CERT_CONTEXT = NULL
+
 ; WinHTTP error codes  ;
 Global Const $WINHTTP_ERROR_BASE = 12000
 Global Const $ERROR_WINHTTP_OUT_OF_HANDLES = 12001
@@ -447,4 +449,4 @@ Global Const $WINHTTP_AUTOPROXY_CONFIG_URL = 0x00000002
 Global Const $WINHTTP_AUTOPROXY_RUN_INPROCESS = 0x00010000
 Global Const $WINHTTP_AUTOPROXY_RUN_OUTPROCESS_ONLY = 0x00020000
 Global Const $WINHTTP_AUTO_DETECT_TYPE_DHCP = 0x00000001
-Global Const $WINHTTP_AUTO_DETECT_TYPE_DNS_A = 0x00000002
\ No newline at end of file
+Global Const $WINHTTP_AUTO_DETECT_TYPE_DNS_A = 0x00000002