diff --git a/lib/curl_sasl_sspi.c b/lib/curl_sasl_sspi.c
index 78d669b948b2376e1ad2ef58c921ee3128a7b29e..ffc569c096ff1db16130874f6d950103d46dc72c 100644
--- a/lib/curl_sasl_sspi.c
+++ b/lib/curl_sasl_sspi.c
@@ -19,6 +19,7 @@
  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  * KIND, either express or implied.
  *
+ * RFC2617 Basic and Digest Access Authentication
  * RFC2831 DIGEST-MD5 authentication
  * RFC4422 Simple Authentication and Security Layer (SASL)
  * RFC4752 The Kerberos V5 ("GSSAPI") SASL Mechanism