diff --git a/cargo-dylint/tests/boundary_toolchains.rs b/cargo-dylint/tests/boundary_toolchains.rs
index 93862500f..d8ce9a9db 100644
--- a/cargo-dylint/tests/boundary_toolchains.rs
+++ b/cargo-dylint/tests/boundary_toolchains.rs
@@ -6,10 +6,21 @@ use dylint_internal::{
 };
 use tempfile::tempdir;
 
-// smoelius: The channel date is one day later than the `rustc --version` date.
+// smoelius: The channel date is one day later than the `rustc --version` date. For example, suppose
+// the code contains:
+// ```
+// #[rustversion::since(2024-03-29)] ...
+// ```
+// Then the boundary should be:
+// ```
+// ("2024-03-29", "2024-03-30"),
+// ```
 // smoelius: Put recent boundaries first, since they're more likely to cause problems.
 // smoelius: The relevant PRs and merge commits appear before each boundary.
 const BOUNDARIES: &[(&str, &str)] = &[
+    // https://github.com/rust-lang/rust/pull/122450
+    // https://github.com/rust-lang/rust/commit/685927aae69657b46323cffbeb0062835bd7fa2b
+    ("2024-03-29", "2024-03-30"),
     // https://github.com/rust-lang/rust/pull/121780
     // https://github.com/rust-lang/rust/commit/1547c076bfec8abb819d6a81e1e4095d267bd5b4
     // https://github.com/rust-lang/rust/pull/121969
diff --git a/utils/linting/src/lib.rs b/utils/linting/src/lib.rs
index cb0e9a636..70c61aef9 100644
--- a/utils/linting/src/lib.rs
+++ b/utils/linting/src/lib.rs
@@ -671,11 +671,20 @@ fn local_crate_source_file(sess: &rustc_session::Session) -> Option<PathBuf> {
 // smoelius: Relevant PR and merge commit:
 // - https://github.com/rust-lang/rust/pull/106810
 // - https://github.com/rust-lang/rust/commit/65d2f2a5f9c323c88d1068e8e90d0b47a20d491c
-#[rustversion::since(2023-01-19)]
+#[rustversion::all(since(2023-01-19), before(2024-03-29))]
 fn local_crate_source_file(sess: &rustc_session::Session) -> Option<PathBuf> {
     sess.local_crate_source_file()
 }
 
+// smoelius: Relevant PR and merge commit:
+// - https://github.com/rust-lang/rust/pull/122450
+// - https://github.com/rust-lang/rust/commit/685927aae69657b46323cffbeb0062835bd7fa2b
+#[rustversion::since(2024-03-29)]
+fn local_crate_source_file(sess: &rustc_session::Session) -> Option<PathBuf> {
+    sess.local_crate_source_file()
+        .and_then(rustc_span::RealFileName::into_local_path)
+}
+
 #[rustversion::before(2023-06-28)]
 fn early_error(msg: String) -> ! {
     rustc_session::early_error(