diff --git a/include/winhttp.h b/include/winhttp.h
index 17fc38a8f02..68bec0a433d 100644
--- a/include/winhttp.h
+++ b/include/winhttp.h
@@ -429,6 +429,11 @@ typedef int INTERNET_SCHEME, *LPINTERNET_SCHEME;
 #define WINHTTP_CALLBACK_STATUS_FLAG_CERT_WRONG_USAGE        0x00000040
 #define WINHTTP_CALLBACK_STATUS_FLAG_SECURITY_CHANNEL_ERROR  0x80000000
 
+#define WINHTTP_FLAG_SECURE_PROTOCOL_SSL2  0x00000008
+#define WINHTTP_FLAG_SECURE_PROTOCOL_SSL3  0x00000020
+#define WINHTTP_FLAG_SECURE_PROTOCOL_TLS1  0x00000080
+#define WINHTTP_FLAG_SECURE_PROTOCOL_ALL   (WINHTTP_FLAG_SECURE_PROTOCOL_SSL2 | WINHTTP_FLAG_SECURE_PROTOCOL_SSL3 | WINHTTP_FLAG_SECURE_PROTOCOL_TLS1)
+
 #define WINHTTP_AUTH_SCHEME_BASIC      0x00000001
 #define WINHTTP_AUTH_SCHEME_NTLM       0x00000002
 #define WINHTTP_AUTH_SCHEME_PASSPORT   0x00000004