diff --git a/src/protocols/vnc/auth.h b/src/protocols/vnc/auth.h
index e978aa9..155a48d 100644
--- a/src/protocols/vnc/auth.h
+++ b/src/protocols/vnc/auth.h
@@ -47,6 +47,10 @@
  *     The rfbClient associated with the VNC connection requiring the
  *     authentication.
  * 
+ * @param credentialType
+ *     The credential type being requested, as defined by the libVNCclient
+ *     code in the rfbclient.h header.
+ * 
  * @return
  *     The rfbCredential object that contains the required credentials.
  */