diff --git a/crankshaft-config/src/backend/generic/driver/shell.rs b/crankshaft-config/src/backend/generic/driver/shell.rs
index 7f3468f..57dcc11 100644
--- a/crankshaft-config/src/backend/generic/driver/shell.rs
+++ b/crankshaft-config/src/backend/generic/driver/shell.rs
@@ -23,7 +23,7 @@ pub enum Shell {
 impl Shell {
     /// Gets a series of args that can be passed through to a driver for
     /// commands.
-    pub fn args<I, S>(&self, args: I) -> impl Iterator<Item = OsString>
+    pub fn args<I, S>(&self, args: I) -> impl Iterator<Item = OsString> + use<I, S>
     where
         I: IntoIterator<Item = OsString>,
     {
diff --git a/crankshaft-engine/src/service/runner/backend/generic.rs b/crankshaft-engine/src/service/runner/backend/generic.rs
index c0b3894..2b6817b 100644
--- a/crankshaft-engine/src/service/runner/backend/generic.rs
+++ b/crankshaft-engine/src/service/runner/backend/generic.rs
@@ -152,38 +152,41 @@ impl crate::Backend for Backend {
                 let output = driver.run(submit).await.unwrap();
 
                 // (2) Monitoring the output.
-                if let Some(ref regex) = job_id_regex {
-                    let stdout = String::from_utf8_lossy(&output.stdout);
-                    let captures = regex.captures_iter(&stdout).next().unwrap_or_else(|| {
-                        panic!(
-                            "could not match the job id regex within stdout: `{}`",
-                            stdout
-                        )
-                    });
-
-                    // SAFETY: this will always unwrap, as the group is
-                    // _required_ for the pattern to match.
-                    let id = captures.get(1).map(|c| String::from(c.as_str())).unwrap();
-                    subtitutions.insert(String::from("job_id"), id);
-
-                    loop {
-                        let monitor = config.resolve_monitor(&subtitutions).unwrap();
-                        let output = driver.run(monitor).await.unwrap();
-
-                        if !output.status.success() {
-                            outputs.push(output);
-                            break;
+                match job_id_regex {
+                    Some(ref regex) => {
+                        let stdout = String::from_utf8_lossy(&output.stdout);
+                        let captures = regex.captures_iter(&stdout).next().unwrap_or_else(|| {
+                            panic!(
+                                "could not match the job id regex within stdout: `{}`",
+                                stdout
+                            )
+                        });
+
+                        // SAFETY: this will always unwrap, as the group is
+                        // _required_ for the pattern to match.
+                        let id = captures.get(1).map(|c| String::from(c.as_str())).unwrap();
+                        subtitutions.insert(String::from("job_id"), id);
+
+                        loop {
+                            let monitor = config.resolve_monitor(&subtitutions).unwrap();
+                            let output = driver.run(monitor).await.unwrap();
+
+                            if !output.status.success() {
+                                outputs.push(output);
+                                break;
+                            }
+
+                            tokio::time::sleep(Duration::from_secs(
+                                config
+                                    .monitor_frequency()
+                                    .unwrap_or(DEFAULT_MONITOR_FREQUENCY),
+                            ))
+                            .await;
                         }
-
-                        tokio::time::sleep(Duration::from_secs(
-                            config
-                                .monitor_frequency()
-                                .unwrap_or(DEFAULT_MONITOR_FREQUENCY),
-                        ))
-                        .await;
                     }
-                } else {
-                    outputs.push(output);
+                    _ => {
+                        outputs.push(output);
+                    }
                 }
             }
 
diff --git a/crankshaft-engine/src/task/builder.rs b/crankshaft-engine/src/task/builder.rs
index 5d7b136..3a0dfb1 100644
--- a/crankshaft-engine/src/task/builder.rs
+++ b/crankshaft-engine/src/task/builder.rs
@@ -96,15 +96,14 @@ impl Builder {
                 inputs.extend(new);
                 Some(inputs)
             }
-            None => {
-                if let Some(input) = new.next() {
+            None => match new.next() {
+                Some(input) => {
                     let mut inputs = NonEmpty::new(input);
                     inputs.extend(new);
                     Some(inputs)
-                } else {
-                    None
                 }
-            }
+                _ => None,
+            },
         };
 
         self
@@ -122,15 +121,14 @@ impl Builder {
                 outputs.extend(new);
                 Some(outputs)
             }
-            None => {
-                if let Some(output) = new.next() {
+            None => match new.next() {
+                Some(output) => {
                     let mut outputs = NonEmpty::new(output);
                     outputs.extend(new);
                     Some(outputs)
-                } else {
-                    None
                 }
-            }
+                _ => None,
+            },
         };
 
         self
@@ -159,15 +157,14 @@ impl Builder {
                 executors.extend(new);
                 Some(executors)
             }
-            None => {
-                if let Some(executor) = new.next() {
+            None => match new.next() {
+                Some(executor) => {
                     let mut executors = NonEmpty::new(executor);
                     executors.extend(new);
                     Some(executors)
-                } else {
-                    None
                 }
-            }
+                _ => None,
+            },
         };
 
         self
@@ -185,15 +182,14 @@ impl Builder {
                 volumes.extend(new);
                 Some(volumes)
             }
-            None => {
-                if let Some(volume) = new.next() {
+            None => match new.next() {
+                Some(volume) => {
                     let mut volumes: NonEmpty<_> = NonEmpty::new(volume);
                     volumes.extend(new);
                     Some(volumes)
-                } else {
-                    None
                 }
-            }
+                _ => None,
+            },
         };
 
         self
diff --git a/crankshaft-engine/src/task/execution/builder.rs b/crankshaft-engine/src/task/execution/builder.rs
index 8fd0a18..cc51b75 100644
--- a/crankshaft-engine/src/task/execution/builder.rs
+++ b/crankshaft-engine/src/task/execution/builder.rs
@@ -89,15 +89,14 @@ impl Builder {
                 args.extend(values);
                 Some(args)
             }
-            None => {
-                if let Some(arg) = values.next() {
+            None => match values.next() {
+                Some(arg) => {
                     let mut args = NonEmpty::new(arg);
                     args.extend(values);
                     Some(args)
-                } else {
-                    None
                 }
-            }
+                _ => None,
+            },
         };
 
         self
diff --git a/crankshaft-engine/src/task/resources/builder.rs b/crankshaft-engine/src/task/resources/builder.rs
index 36dcb65..7c21163 100644
--- a/crankshaft-engine/src/task/resources/builder.rs
+++ b/crankshaft-engine/src/task/resources/builder.rs
@@ -90,15 +90,14 @@ impl Builder {
                 zones.extend(values);
                 Some(zones)
             }
-            None => {
-                if let Some(zone) = values.next() {
+            None => match values.next() {
+                Some(zone) => {
                     let mut zones = NonEmpty::new(zone);
                     zones.extend(values);
                     Some(zones)
-                } else {
-                    None
                 }
-            }
+                _ => None,
+            },
         };
 
         self