diff --git a/bevy_lint/src/lib.rs b/bevy_lint/src/lib.rs
index 42c76e1e..c84683ab 100644
--- a/bevy_lint/src/lib.rs
+++ b/bevy_lint/src/lib.rs
@@ -2,6 +2,8 @@
 #![feature(rustc_private)]
 // Allows chaining `if let` multiple times using `&&`.
 #![feature(let_chains)]
+// Warn on internal `rustc` lints that check for poor usage of internal compiler APIs.
+#![warn(rustc::internal)]
 
 // This is a list of every single `rustc` crate used within this library. If you need another, add
 // it here!
diff --git a/bevy_lint/tests/ui.rs b/bevy_lint/tests/ui.rs
index 2213ef43..ea5e2f00 100644
--- a/bevy_lint/tests/ui.rs
+++ b/bevy_lint/tests/ui.rs
@@ -82,8 +82,10 @@ fn config() -> color_eyre::Result<Config> {
 #[derive(Deserialize, Debug)]
 #[serde(rename = "compiler-artifact", tag = "reason")]
 struct ArtifactMessage<'a> {
-    package_id: &'a str,
+    #[serde(borrow)]
     target: ArtifactTarget<'a>,
+
+    #[serde(borrow)]
     filenames: Vec<&'a Path>,
 }
 
@@ -91,6 +93,8 @@ struct ArtifactMessage<'a> {
 #[derive(Deserialize, Debug)]
 struct ArtifactTarget<'a> {
     name: &'a str,
+
+    #[serde(borrow)]
     kind: Vec<&'a str>,
 }
 
@@ -114,19 +118,17 @@ fn find_bevy_rlib() -> color_eyre::Result<PathBuf> {
 
     ensure!(output.status.success(), "`cargo build --test=ui` failed.");
 
-    // The package ID of the `bevy` crate starts with this string.
-    const BEVY_PACKAGE_ID_PREFIX: &str =
-        "registry+https://github.com/rust-lang/crates.io-index#bevy@";
-
     // It's theoretically possible for there to be multiple messages about building `libbevy.rlib`.
     // We support this, but optimize for just 1 message.
     let mut messages = Vec::with_capacity(1);
 
+    // Convert the `stdout` to a string, replacing invalid characters with `�`.
+    let stdout = String::from_utf8_lossy(&output.stdout);
+
     // Iterate over each line in stdout, trying to deserialize it from JSON.
-    for line in output.stdout.split(|&byte| byte == b'\n') {
-        if let Ok(message) = serde_json::from_slice::<ArtifactMessage>(line)
+    for line in stdout.lines() {
+        if let Ok(message) = serde_json::from_str::<ArtifactMessage>(line)
             // If the message passes the following conditions, it's probably the one we want.
-            && message.package_id.starts_with(BEVY_PACKAGE_ID_PREFIX)
             && message.target.name == "bevy"
             && message.target.kind.contains(&"lib")
         {
diff --git a/bevy_lint/tests/ui/main_return_without_appexit.rs b/bevy_lint/tests/ui/main_return_without_appexit.rs
new file mode 100644
index 00000000..8e6cffb1
--- /dev/null
+++ b/bevy_lint/tests/ui/main_return_without_appexit.rs
@@ -0,0 +1,10 @@
+#![feature(register_tool)]
+#![register_tool(bevy)]
+#![deny(bevy::main_return_without_appexit)]
+
+use bevy::prelude::*;
+
+fn main() {
+    App::new().run();
+    //~^ ERROR: an entrypoint that calls `App::run()` does not return `AppExit`
+}
diff --git a/bevy_lint/tests/ui/main_return_without_appexit.stderr b/bevy_lint/tests/ui/main_return_without_appexit.stderr
new file mode 100644
index 00000000..c5b137f0
--- /dev/null
+++ b/bevy_lint/tests/ui/main_return_without_appexit.stderr
@@ -0,0 +1,17 @@
+error: an entrypoint that calls `App::run()` does not return `AppExit`
+ --> tests/ui/main_return_without_appexit.rs:8:16
+  |
+7 | fn main() {
+  |          - help: try: `-> AppExit`
+8 |     App::new().run();
+  |                ^^^^^
+  |
+  = note: `App::run()` returns `AppExit`, which can be used to determine whether the app exited successfully or not
+note: the lint level is defined here
+ --> tests/ui/main_return_without_appexit.rs:3:9
+  |
+3 | #![deny(bevy::main_return_without_appexit)]
+  |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+