diff --git a/lib/net/http.rb b/lib/net/http.rb
index 05d82db12f..3f16ff8df5 100644
--- a/lib/net/http.rb
+++ b/lib/net/http.rb
@@ -465,6 +465,8 @@ module Net   #:nodoc:
     #   { "cmd" => "search", "q" => "ruby", "max" => "50" }
     #
     # This method also does Basic Authentication iff +url+.user exists.
+    # But userinfo for authentication is deprecated (RFC3986).
+    # So this feature will be removed.
     #
     # Example:
     #