diff --git a/components/config/basedir.rs b/components/config/basedir.rs
index fbae2a7edca..fd17e482b88 100644
--- a/components/config/basedir.rs
+++ b/components/config/basedir.rs
@@ -35,7 +35,7 @@ pub fn default_config_dir() -> Option<PathBuf> {
     Some(config_dir)
 }
 
-#[cfg(all(target_os = "windows"))]
+#[cfg(target_os = "windows")]
 pub fn default_config_dir() -> Option<PathBuf> {
     let mut config_dir = ::dirs_next::config_dir().unwrap();
     config_dir.push("Servo");
diff --git a/components/config/opts.rs b/components/config/opts.rs
index 5cf394bb297..43348fccc2e 100644
--- a/components/config/opts.rs
+++ b/components/config/opts.rs
@@ -7,7 +7,7 @@
 
 use std::default::Default;
 use std::fs::{self, File};
-use std::io::{self, Read, Write};
+use std::io::Read;
 use std::path::{Path, PathBuf};
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{RwLock, RwLockReadGuard};
@@ -385,7 +385,7 @@ pub enum OutputOptions {
 }
 
 fn args_fail(msg: &str) -> ! {
-    writeln!(io::stderr(), "{}", msg).unwrap();
+    eprintln!("{}", msg);
     process::exit(1)
 }
 
@@ -793,7 +793,7 @@ pub fn from_cmdline_args(mut opts: Options, args: &[String]) -> ArgumentParsingR
         set_pref!(layout.threads, layout_threads as i64);
     }
 
-    return ArgumentParsingResult::ChromeProcess(opt_match);
+    ArgumentParsingResult::ChromeProcess(opt_match)
 }
 
 pub enum ArgumentParsingResult {
diff --git a/components/config/pref_util.rs b/components/config/pref_util.rs
index 11e2f7f94a8..d8cfa78aaea 100644
--- a/components/config/pref_util.rs
+++ b/components/config/pref_util.rs
@@ -55,10 +55,7 @@ impl PrefValue {
     }
 
     pub fn is_missing(&self) -> bool {
-        match self {
-            PrefValue::Missing => true,
-            _ => false,
-        }
+        matches!(self, PrefValue::Missing)
     }
 
     pub fn from_json_value(value: &Value) -> Option<Self> {
@@ -164,7 +161,7 @@ impl From<PrefValue> for [f64; 4] {
                 let mut f = values.into_iter().map(|v| v.try_into());
                 if f.all(|v| v.is_ok()) {
                     let f = f.flatten().collect::<Vec<f64>>();
-                    return [f[0], f[1], f[2], f[3]];
+                    [f[0], f[1], f[2], f[3]]
                 } else {
                     panic!(
                         "Cannot convert PrefValue to {:?}",
@@ -191,7 +188,7 @@ pub enum PrefError {
 impl fmt::Display for PrefError {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
-            PrefError::NoSuchPref(s) | PrefError::InvalidValue(s) => f.write_str(&s),
+            PrefError::NoSuchPref(s) | PrefError::InvalidValue(s) => f.write_str(s),
             PrefError::JsonParseErr(e) => e.fmt(f),
         }
     }
@@ -201,6 +198,7 @@ impl std::error::Error for PrefError {}
 
 pub struct Accessor<P, V> {
     pub getter: Box<dyn Fn(&P) -> V + Sync>,
+    #[allow(clippy::type_complexity)]
     pub setter: Box<dyn Fn(&mut P, V) + Sync>,
 }
 
@@ -261,7 +259,7 @@ impl<'m, P: Clone> Preferences<'m, P> {
     }
 
     /// Creates an iterator over all keys and values
-    pub fn iter<'a>(&'a self) -> impl Iterator<Item = (String, PrefValue)> + 'a {
+    pub fn iter(&self) -> impl Iterator<Item = (String, PrefValue)> + '_ {
         let prefs = self.user_prefs.read().unwrap();
         self.accessors
             .iter()
@@ -269,16 +267,17 @@ impl<'m, P: Clone> Preferences<'m, P> {
     }
 
     /// Creates an iterator over all keys
-    pub fn keys<'a>(&'a self) -> impl Iterator<Item = &'a str> + 'a {
+    pub fn keys(&self) -> impl Iterator<Item = &'_ str> {
         self.accessors.keys().map(String::as_str)
     }
 
-    fn set_inner<V>(&self, key: &str, mut prefs: &mut P, val: V) -> Result<(), PrefError>
+    fn set_inner<V>(&self, key: &str, prefs: &mut P, val: V) -> Result<(), PrefError>
     where
         V: Into<PrefValue>,
     {
         if let Some(accessor) = self.accessors.get(key) {
-            Ok((accessor.setter)(&mut prefs, val.into()))
+            (accessor.setter)(prefs, val.into());
+            Ok(())
         } else {
             Err(PrefError::NoSuchPref(String::from(key)))
         }
diff --git a/components/config/prefs.rs b/components/config/prefs.rs
index 826605da6d9..f9c7c39bf82 100644
--- a/components/config/prefs.rs
+++ b/components/config/prefs.rs
@@ -67,7 +67,7 @@ pub fn add_user_prefs(prefs: HashMap<String, PrefValue>) {
     for (key, value) in prefs.iter() {
         set_stylo_pref_ref(key, value);
     }
-    if let Err(error) = PREFS.set_all(prefs.into_iter()) {
+    if let Err(error) = PREFS.set_all(prefs) {
         panic!("Error setting preference: {:?}", error);
     }
 }
@@ -106,15 +106,15 @@ impl TryFrom<&PrefValue> for StyloPrefValue {
     type Error = TryFromPrefValueError;
 
     fn try_from(value: &PrefValue) -> Result<Self, Self::Error> {
-        match value {
-            &PrefValue::Int(value) => {
+        match *value {
+            PrefValue::Int(value) => {
                 if let Ok(value) = value.try_into() {
                     Ok(Self::Int(value))
                 } else {
                     Err(TryFromPrefValueError::IntegerOverflow(value))
                 }
             },
-            &PrefValue::Bool(value) => Ok(Self::Bool(value)),
+            PrefValue::Bool(value) => Ok(Self::Bool(value)),
             _ => Err(TryFromPrefValueError::UnmappedType),
         }
     }
@@ -122,7 +122,7 @@ impl TryFrom<&PrefValue> for StyloPrefValue {
 
 pub fn read_prefs_map(txt: &str) -> Result<HashMap<String, PrefValue>, PrefError> {
     let prefs: HashMap<String, Value> =
-        serde_json::from_str(txt).map_err(|e| PrefError::JsonParseErr(e))?;
+        serde_json::from_str(txt).map_err(PrefError::JsonParseErr)?;
     prefs
         .into_iter()
         .map(|(k, pref_value)| {
@@ -133,7 +133,7 @@ pub fn read_prefs_map(txt: &str) -> Result<HashMap<String, PrefValue>, PrefError
                     Value::Number(n) if n.is_f64() => PrefValue::Float(n.as_f64().unwrap()),
                     Value::String(s) => PrefValue::Str(s.to_owned()),
                     Value::Array(v) => {
-                        let mut array = v.iter().map(|v| PrefValue::from_json_value(v));
+                        let mut array = v.iter().map(PrefValue::from_json_value);
                         if array.all(|v| v.is_some()) {
                             PrefValue::Array(array.flatten().collect())
                         } else {
diff --git a/components/config_plugins/parse.rs b/components/config_plugins/parse.rs
index 3a390f2f07f..63a3d66dfda 100644
--- a/components/config_plugins/parse.rs
+++ b/components/config_plugins/parse.rs
@@ -132,7 +132,7 @@ impl Parse for RootTypeDef {
 impl Parse for NewTypeDef {
     fn parse(input: ParseStream<'_>) -> Result<Self> {
         let content;
-        #[allow(clippy::eval_order_dependence)]
+        #[allow(clippy::mixed_read_write_in_expression)]
         Ok(NewTypeDef {
             _braces: braced!(content in input),
             fields: Punctuated::parse_terminated_with(&content, Field::parse)?,