diff --git a/clap_derive/src/derives/subcommand.rs b/clap_derive/src/derives/subcommand.rs
index b4a955ffdb0..8d73ce610e9 100644
--- a/clap_derive/src/derives/subcommand.rs
+++ b/clap_derive/src/derives/subcommand.rs
@@ -1,3 +1,16 @@
+// Copyright 2018 Guillaume Pinot (@TeXitoi) <texitoi@texitoi.eu>,
+// Kevin Knapp (@kbknapp) <kbknapp@gmail.com>, and
+// Andrew Hobden (@hoverbear) <andrew@hoverbear.org>
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+//
+// This work was derived from Structopt (https://github.com/TeXitoi/structopt)
+// commit#ea76fa1b1b273e65e3b0b1046643715b49bec51f which is licensed under the
+// MIT/Apache 2.0 license.
 use crate::{
     attrs::{Attrs, Kind, Name, DEFAULT_CASING, DEFAULT_ENV_CASING},
     derives::args,
diff --git a/clap_derive/tests/ui/enum_variant_not_args.rs b/clap_derive/tests/ui/enum_variant_not_args.rs
new file mode 100644
index 00000000000..8628b925881
--- /dev/null
+++ b/clap_derive/tests/ui/enum_variant_not_args.rs
@@ -0,0 +1,9 @@
+#[derive(clap::Clap)]
+enum Opt {
+    Sub(SubCmd),
+}
+
+#[derive(clap::Clap)]
+enum SubCmd {}
+
+fn main() {}
diff --git a/clap_derive/tests/ui/enum_variant_not_args.stderr b/clap_derive/tests/ui/enum_variant_not_args.stderr
new file mode 100644
index 00000000000..f1a9b207a44
--- /dev/null
+++ b/clap_derive/tests/ui/enum_variant_not_args.stderr
@@ -0,0 +1,7 @@
+error[E0277]: the trait bound `SubCmd: clap::Args` is not satisfied
+ --> $DIR/enum_variant_not_args.rs:3:9
+  |
+3 |     Sub(SubCmd),
+  |         ^^^^^^ the trait `clap::Args` is not implemented for `SubCmd`
+  |
+  = note: required by `augment_args`
diff --git a/clap_derive/tests/ui/flatten_on_subcommand.rs b/clap_derive/tests/ui/flatten_on_subcommand.rs
new file mode 100644
index 00000000000..ad7cd5a038e
--- /dev/null
+++ b/clap_derive/tests/ui/flatten_on_subcommand.rs
@@ -0,0 +1,10 @@
+#[derive(clap::Clap)]
+struct Opt {
+    #[clap(flatten)]
+    sub: SubCmd,
+}
+
+#[derive(clap::Clap)]
+enum SubCmd {}
+
+fn main() {}
diff --git a/clap_derive/tests/ui/flatten_on_subcommand.stderr b/clap_derive/tests/ui/flatten_on_subcommand.stderr
new file mode 100644
index 00000000000..cc753951667
--- /dev/null
+++ b/clap_derive/tests/ui/flatten_on_subcommand.stderr
@@ -0,0 +1,7 @@
+error[E0277]: the trait bound `SubCmd: clap::Args` is not satisfied
+ --> $DIR/flatten_on_subcommand.rs:3:12
+  |
+3 |     #[clap(flatten)]
+  |            ^^^^^^^ the trait `clap::Args` is not implemented for `SubCmd`
+  |
+  = note: required by `augment_args`