diff --git a/lib/url.c b/lib/url.c
index 5705252c4..3439e292a 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -1501,7 +1501,7 @@ CURLcode Curl_setopt(struct SessionHandle *data, CURLoption option,
 
   case CURLOPT_SERVICE_NAME:
     /*
-     * Set negotiate service identity
+     * Set authentication service name for DIGEST-MD5, Kerberos 5 and SPNEGO
      */
     result = setstropt(&data->set.str[STRING_SERVICE_NAME],
                        va_arg(param, char *));
diff --git a/src/tool_cfgable.h b/src/tool_cfgable.h
index fb6c7aec4..fba5617ad 100644
--- a/src/tool_cfgable.h
+++ b/src/tool_cfgable.h
@@ -7,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2016, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -171,8 +171,8 @@ struct OperationConfig {
                              * default HTTP */
   int socks5_gssapi_nec ;   /* The NEC reference server does not protect
                              * the encryption type exchange */
-  char *service_name;       /* set negotiation service name
-                             * default HTTP */
+  char *service_name;       /* set authentication service name for DIGEST-MD5,
+                               Kerberos 5 and SPNEGO */
 
   bool tcp_nodelay;
   long req_retry;           /* number of retries */