diff --git a/television/channels/cable.rs b/television/channels/cable.rs
index a64140d..af5b60b 100644
--- a/television/channels/cable.rs
+++ b/television/channels/cable.rs
@@ -152,6 +152,7 @@ async fn load_candidates(
             if let Ok(l) = line {
                 if !l.trim().is_empty() {
                     let () = injector.push(l, |e, cols| {
+                        // PERF: maybe we can avoid cloning here by using &Utf32Str
                         cols[0] = e.clone().into();
                     });
                     produced_output = true;
diff --git a/television/channels/prototypes.rs b/television/channels/prototypes.rs
index d636baf..f0ecba2 100644
--- a/television/channels/prototypes.rs
+++ b/television/channels/prototypes.rs
@@ -95,6 +95,19 @@ impl Display for ChannelPrototype {
 
 pub static CMD_RE: &Lazy<Regex> = regex!(r"\{(\d+)\}");
 
+/// Formats a prototype string with the given template and source strings.
+///
+/// # Example
+/// ```
+/// use television::channels::prototypes::format_prototype_string;
+///
+/// let template = "cat {} {1}";
+/// let source = "foo:bar:baz";
+/// let delimiter = ":";
+///
+/// let formatted = format_prototype_string(template, source, delimiter);
+/// assert_eq!(formatted, "cat 'foo:bar:baz' 'bar'");
+/// ```
 pub fn format_prototype_string(
     template: &str,
     source: &str,
@@ -108,8 +121,9 @@ pub fn format_prototype_string(
     formatted_string = CMD_RE
         .replace_all(&formatted_string, |caps: &regex::Captures| {
             let index =
+                // these unwraps are safe because of the regex pattern
                 caps.get(1).unwrap().as_str().parse::<usize>().unwrap();
-            format!("'{}'", parts[index])
+            format!("'{}'", parts.get(index).unwrap_or(&""))
         })
         .to_string();
 
diff --git a/television/previewer/mod.rs b/television/previewer/mod.rs
index 96c93ae..afbf32c 100644
--- a/television/previewer/mod.rs
+++ b/television/previewer/mod.rs
@@ -131,10 +131,11 @@ impl Preview {
 
 pub struct Previewer {
     config: Config,
+    // FIXME: maybe use a bounded channel here with a single slot
     requests: UnboundedReceiver<Request>,
     last_job_entry: Option<Entry>,
     preview_command: PreviewCommand,
-    previews: UnboundedSender<Preview>,
+    results: UnboundedSender<Preview>,
 }
 
 impl Previewer {
@@ -149,7 +150,7 @@ impl Previewer {
             requests: receiver,
             last_job_entry: None,
             preview_command,
-            previews: sender,
+            results: sender,
         }
     }
 
@@ -166,7 +167,7 @@ impl Previewer {
                             debug!("Preview request is stale, skipping");
                             continue;
                         }
-                        let notify = self.previews.clone();
+                        let results_handle = self.results.clone();
                         let command =
                             self.preview_command.format_with(&ticket.entry);
                         self.last_job_entry = Some(ticket.entry.clone());
@@ -174,7 +175,11 @@ impl Previewer {
                         match timeout(
                             self.config.job_timeout,
                             tokio::spawn(async move {
-                                try_preview(&command, &ticket.entry, &notify);
+                                try_preview(
+                                    &command,
+                                    &ticket.entry,
+                                    &results_handle,
+                                );
                             }),
                         )
                         .await
@@ -203,7 +208,7 @@ impl Previewer {
 pub fn try_preview(
     command: &str,
     entry: &Entry,
-    notify: &UnboundedSender<Preview>,
+    results_handle: &UnboundedSender<Preview>,
 ) {
     debug!("Preview command: {}", command);
 
@@ -241,7 +246,7 @@ pub fn try_preview(
             )
         }
     };
-    notify
+    results_handle
         .send(preview)
         .expect("Unable to send preview result to main thread.");
 }