diff --git a/src/cmd/serve.rs b/src/cmd/serve.rs
index 97de19f5..e9209b63 100644
--- a/src/cmd/serve.rs
+++ b/src/cmd/serve.rs
@@ -83,8 +83,9 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
         .config
         .get("output.html.input-404")
         .map(toml::Value::as_str)
-        .flatten();
-    let file_404 = get_404_output_file(input_404);
+        .flatten()
+        .map(ToString::to_string);
+    let file_404 = get_404_output_file(&input_404);
 
     // A channel used to broadcast to any websockets to reload when a file changes.
     let (tx, _rx) = tokio::sync::broadcast::channel::<Message>(100);
diff --git a/src/config.rs b/src/config.rs
index f6825c39..cbcf3e91 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -1023,7 +1023,7 @@ mod tests {
         let html_config = got.html_config().unwrap();
         assert_eq!(html_config.input_404, None);
         assert_eq!(
-            &get_404_output_file(html_config.input_404.as_deref()),
+            &get_404_output_file(&html_config.input_404),
             "404.html"
         );
     }
@@ -1040,7 +1040,7 @@ mod tests {
         let html_config = got.html_config().unwrap();
         assert_eq!(html_config.input_404, Some("missing.md".to_string()));
         assert_eq!(
-            &get_404_output_file(html_config.input_404.as_deref()),
+            &get_404_output_file(&html_config.input_404),
             "missing.html"
         );
     }
diff --git a/src/renderer/html_handlebars/hbs_renderer.rs b/src/renderer/html_handlebars/hbs_renderer.rs
index dcc12579..e1ca9a15 100644
--- a/src/renderer/html_handlebars/hbs_renderer.rs
+++ b/src/renderer/html_handlebars/hbs_renderer.rs
@@ -152,7 +152,7 @@ impl HtmlHandlebars {
         let rendered = handlebars.render("index", &data_404)?;
 
         let rendered = self.post_process(rendered, &html_config.playpen, ctx.config.rust.edition);
-        let output_file = get_404_output_file(html_config.input_404.as_deref());
+        let output_file = get_404_output_file(&html_config.input_404);
         utils::fs::write_file(&destination, output_file, rendered.as_bytes())?;
         debug!("Creating 404.html ✓");
         Ok(())
diff --git a/src/utils/fs.rs b/src/utils/fs.rs
index 6b7529db..a1bea133 100644
--- a/src/utils/fs.rs
+++ b/src/utils/fs.rs
@@ -177,8 +177,8 @@ pub fn copy_files_except_ext(
     Ok(())
 }
 
-pub fn get_404_output_file(input_404: Option<&str>) -> String {
-    input_404.unwrap_or("404.md").replace(".md", ".html")
+pub fn get_404_output_file(input_404: &Option<String>) -> String {
+    input_404.as_ref().unwrap_or(&"404.md".to_string()).replace(".md", ".html")
 }
 
 #[cfg(test)]