diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9aa58bc..5048238 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,13 @@
 # SpamAssassin Milter changelog
 
+## 0.4.1 (unreleased)
+
+### Added
+
+* Add `--synth-relay` option to allow inserting the synthesised internal relay
+  header (the MTA’s `Received` header) at a different position than at the very
+  beginning.
+
 ## 0.4.0 (2023-01-29)
 
 The minimum supported Rust version is now 1.61.0.
@@ -15,12 +23,6 @@ The minimum supported Rust version is now 1.61.0.
 
 ## 0.3.2 (2022-08-31)
 
-### Added
-
-* Add `--synth-relay` option to allow inserting the synthesised internal relay
-  header (the MTA’s `Received` header) at a different position than at the very
-  beginning.
-
 ### Changed
 
 * The command-line user interface has been reimplemented using a lighter-weight,
diff --git a/src/callbacks.rs b/src/callbacks.rs
index a75d89e..500186a 100644
--- a/src/callbacks.rs
+++ b/src/callbacks.rs
@@ -278,7 +278,7 @@ async fn synthesize_relay_header(config: &Config, macros: &Macros, client: &mut
     let id = macros.queue_id();
 
     if config.synth_relay().is_some() {
-        verbose!(config, "{}: inserting synthetic relay header at index {}", id, client.header_count());
+        verbose!(config, "{id}: inserting synthetic relay header at index {}", client.header_count());
     }
 
     // Note that when SpamAssassin reports are enabled (`report_safe 1`), the
diff --git a/src/main.rs b/src/main.rs
index 8cff0ca..05c3242 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -209,7 +209,7 @@ fn parse_args() -> Result<(Socket, Config), Box<dyn Error>> {
             "--synth-relay" => {
                 let arg = args.next().ok_or_else(missing_value)??;
                 let pos = arg.parse()
-                    .map_err(|_| format!("invalid value for synthesized relay header position: \"{}\"", arg))?;
+                    .map_err(|_| format!("invalid value for synthesized relay header position: \"{arg}\""))?;
 
                 config = config.synth_relay(pos);
             }