diff --git a/src/builtin/meta.rs b/src/builtin/meta.rs
index bf7fc02..957391e 100644
--- a/src/builtin/meta.rs
+++ b/src/builtin/meta.rs
@@ -96,7 +96,7 @@ fn variable_exists(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Va
     args.max_args(1)?;
     match parser.arg(&mut args, 0, "name")? {
         Value::String(s, _) => Ok(Value::bool(
-            parser.scopes.var_exists(&s.into(), parser.global_scope),
+            parser.scopes.var_exists(s.into(), parser.global_scope),
         )),
         v => Err((
             format!("$name: {} is not a string.", v.inspect(args.span())?),
@@ -109,7 +109,7 @@ fn variable_exists(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Va
 fn global_variable_exists(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Value> {
     args.max_args(1)?;
     match parser.arg(&mut args, 0, "name")? {
-        Value::String(s, _) => Ok(Value::bool(parser.global_scope.var_exists(&s.into()))),
+        Value::String(s, _) => Ok(Value::bool(parser.global_scope.var_exists(s.into()))),
         v => Err((
             format!("$name: {} is not a string.", v.inspect(args.span())?),
             args.span(),
@@ -122,7 +122,7 @@ fn mixin_exists(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Value
     args.max_args(2)?;
     match parser.arg(&mut args, 0, "name")? {
         Value::String(s, _) => Ok(Value::bool(
-            parser.scopes.mixin_exists(&s.into(), parser.global_scope),
+            parser.scopes.mixin_exists(s.into(), parser.global_scope),
         )),
         v => Err((
             format!("$name: {} is not a string.", v.inspect(args.span())?),
@@ -136,7 +136,7 @@ fn function_exists(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Va
     args.max_args(2)?;
     match parser.arg(&mut args, 0, "name")? {
         Value::String(s, _) => Ok(Value::bool(
-            parser.scopes.fn_exists(&s.into(), parser.global_scope),
+            parser.scopes.fn_exists(s.into(), parser.global_scope),
         )),
         v => Err((
             format!("$name: {} is not a string.", v.inspect(args.span())?),
@@ -183,7 +183,7 @@ fn get_function(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Value
 
     let func = match parser.scopes.get_fn(
         Spanned {
-            node: &name,
+            node: name,
             span: args.span(),
         },
         parser.global_scope,
diff --git a/src/common.rs b/src/common.rs
index 3a4a6fe..554a567 100644
--- a/src/common.rs
+++ b/src/common.rs
@@ -112,7 +112,7 @@ impl ListSeparator {
 ///
 /// This struct protects that invariant by normalizing all
 /// underscores into hypens.
-#[derive(Debug, Clone, Eq, PartialEq, Hash, PartialOrd, Ord)]
+#[derive(Debug, Clone, Eq, PartialEq, Hash, PartialOrd, Ord, Copy)]
 pub(crate) struct Identifier(InternedString);
 
 impl From<String> for Identifier {
diff --git a/src/lib.rs b/src/lib.rs
index 5c0b7af..4d37f1b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -75,6 +75,8 @@ grass input.scss
     clippy::items_after_statements,
     clippy::shadow_reuse,
     clippy::shadow_unrelated,
+    // this is only available on nightly
+    clippy::unnested_or_patterns,
 )]
 #![cfg_attr(feature = "nightly", feature(track_caller))]
 #![cfg_attr(feature = "profiling", inline(never))]
@@ -108,6 +110,7 @@ mod builtin;
 mod color;
 mod common;
 mod error;
+mod interner;
 mod lexer;
 mod output;
 mod parse;
@@ -116,7 +119,6 @@ mod selector;
 mod style;
 mod token;
 mod unit;
-mod interner;
 mod utils;
 mod value;
 
diff --git a/src/parse/args.rs b/src/parse/args.rs
index 0e86c19..1da193c 100644
--- a/src/parse/args.rs
+++ b/src/parse/args.rs
@@ -363,7 +363,7 @@ impl<'a> Parser<'a> {
                 let span = args.span();
                 let arg_list = Value::ArgList(self.variadic_args(args)?);
                 scope.insert_var(
-                    arg.name.clone(),
+                    arg.name,
                     Spanned {
                         node: arg_list,
                         span,
@@ -371,7 +371,7 @@ impl<'a> Parser<'a> {
                 );
                 break;
             }
-            let val = match args.get(idx, arg.name.clone()) {
+            let val = match args.get(idx, arg.name) {
                 Some(v) => v,
                 None => match arg.default.as_mut() {
                     Some(v) => self.parse_value_from_vec(mem::take(v)),
@@ -382,7 +382,7 @@ impl<'a> Parser<'a> {
                     }
                 },
             }?;
-            self.scopes.insert_var(arg.name.clone(), val.clone());
+            self.scopes.insert_var(arg.name, val.clone());
             scope.insert_var(arg.name, val);
         }
         self.scopes.exit_scope();
diff --git a/src/parse/control_flow.rs b/src/parse/control_flow.rs
index 3bd85a0..559f985 100644
--- a/src/parse/control_flow.rs
+++ b/src/parse/control_flow.rs
@@ -295,7 +295,7 @@ impl<'a> Parser<'a> {
 
         for i in iter {
             self.scopes.insert_var(
-                var.node.clone(),
+                var.node,
                 Spanned {
                     node: Value::Dimension(Number::from(i), Unit::None),
                     span: var.span,
@@ -467,7 +467,7 @@ impl<'a> Parser<'a> {
         for row in iter {
             if vars.len() == 1 {
                 self.scopes.insert_var(
-                    vars[0].node.clone(),
+                    vars[0].node,
                     Spanned {
                         node: row,
                         span: vars[0].span,
@@ -480,7 +480,7 @@ impl<'a> Parser<'a> {
                         .chain(std::iter::once(Value::Null).cycle()),
                 ) {
                     self.scopes.insert_var(
-                        var.node.clone(),
+                        var.node,
                         Spanned {
                             node: val,
                             span: var.span,
diff --git a/src/parse/mixin.rs b/src/parse/mixin.rs
index 18c00cf..4add13a 100644
--- a/src/parse/mixin.rs
+++ b/src/parse/mixin.rs
@@ -112,13 +112,7 @@ impl<'a> Parser<'a> {
             args: fn_args,
             declared_at_root,
             ..
-        } = self.scopes.get_mixin(
-            {
-                let Spanned { ref node, span } = name;
-                Spanned { node, span }
-            },
-            self.global_scope,
-        )?;
+        } = self.scopes.get_mixin(name, self.global_scope)?;
 
         let scope = self.eval_args(fn_args, args)?;
 
diff --git a/src/parse/style.rs b/src/parse/style.rs
index 90a5dd6..2ee336c 100644
--- a/src/parse/style.rs
+++ b/src/parse/style.rs
@@ -218,10 +218,7 @@ impl<'a> Parser<'a> {
                                 styles.push(Style { property, value });
                             }
                             Some(Token { kind: '{', .. }) => {
-                                styles.push(Style {
-                                    property: property.clone(),
-                                    value,
-                                });
+                                styles.push(Style { property, value });
                                 styles.append(&mut self.parse_style_group(property)?);
                             }
                             Some(..) | None => {
@@ -254,7 +251,7 @@ impl<'a> Parser<'a> {
                         }
                         '{' => {
                             let mut v = vec![Style {
-                                property: super_property.clone(),
+                                property: super_property,
                                 value: Box::new(value),
                             }];
                             v.append(&mut self.parse_style_group(super_property)?);
diff --git a/src/parse/value/parse.rs b/src/parse/value/parse.rs
index c890ddb..ac1e054 100644
--- a/src/parse/value/parse.rs
+++ b/src/parse/value/parse.rs
@@ -258,7 +258,7 @@ impl<'a> Parser<'a> {
             let as_ident = Identifier::from(&s);
             let func = match self.scopes.get_fn(
                 Spanned {
-                    node: &as_ident,
+                    node: as_ident,
                     span,
                 },
                 self.global_scope,
@@ -528,13 +528,7 @@ impl<'a> Parser<'a> {
                     Err(e) => return Some(Err(e)),
                 };
                 IntermediateValue::Value(HigherIntermediateValue::Literal(
-                    match self.scopes.get_var(
-                        {
-                            let Spanned { ref node, span } = val;
-                            Spanned { node, span }
-                        },
-                        self.global_scope,
-                    ) {
+                    match self.scopes.get_var(val, self.global_scope) {
                         Ok(v) => v.clone(),
                         Err(e) => return Some(Err(e)),
                     },
diff --git a/src/parse/variable.rs b/src/parse/variable.rs
index 0255eff..caad769 100644
--- a/src/parse/variable.rs
+++ b/src/parse/variable.rs
@@ -41,25 +41,23 @@ impl<'a> Parser<'a> {
         let value = self.parse_variable_value()?;
 
         if value.global && !value.default {
-            self.global_scope
-                .insert_var(ident.clone(), value.value.clone());
+            self.global_scope.insert_var(ident, value.value.clone());
         }
 
         if value.default {
             if self.at_root && !self.flags.in_control_flow() {
-                if !self.global_scope.var_exists(&ident) {
+                if !self.global_scope.var_exists(ident) {
                     self.global_scope.insert_var(ident, value.value);
                 }
             } else {
-                if value.global && !self.global_scope.var_exists(&ident) {
-                    self.global_scope
-                        .insert_var(ident.clone(), value.value.clone());
+                if value.global && !self.global_scope.var_exists(ident) {
+                    self.global_scope.insert_var(ident, value.value.clone());
                 }
                 self.scopes.insert_default_var(ident, value.value);
             }
         } else if self.at_root {
             if self.flags.in_control_flow() {
-                if self.global_scope.var_exists(&ident) {
+                if self.global_scope.var_exists(ident) {
                     self.global_scope.insert_var(ident, value.value);
                 } else {
                     self.scopes.insert_var(ident, value.value);
diff --git a/src/scope.rs b/src/scope.rs
index b6b82cd..7ce48de 100644
--- a/src/scope.rs
+++ b/src/scope.rs
@@ -18,6 +18,8 @@ pub(crate) struct Scope {
 }
 
 impl Scope {
+    // `BTreeMap::new` is not yet const
+    #[allow(clippy::missing_const_for_fn)]
     #[must_use]
     pub fn new() -> Self {
         Self {
@@ -27,8 +29,8 @@ impl Scope {
         }
     }
 
-    fn get_var(&self, name: Spanned<&Identifier>) -> SassResult<&Value> {
-        match self.vars.get(name.node) {
+    fn get_var(&self, name: Spanned<Identifier>) -> SassResult<&Value> {
+        match self.vars.get(&name.node) {
             Some(v) => Ok(&v.node),
             None => Err(("Undefined variable.", name.span).into()),
         }
@@ -38,12 +40,12 @@ impl Scope {
         self.vars.insert(s, v)
     }
 
-    pub fn var_exists(&self, name: &Identifier) -> bool {
-        self.vars.contains_key(name)
+    pub fn var_exists(&self, name: Identifier) -> bool {
+        self.vars.contains_key(&name)
     }
 
-    fn get_mixin(&self, name: Spanned<&Identifier>) -> SassResult<Mixin> {
-        match self.mixins.get(name.node) {
+    fn get_mixin(&self, name: Spanned<Identifier>) -> SassResult<Mixin> {
+        match self.mixins.get(&name.node) {
             Some(v) => Ok(v.clone()),
             None => Err(("Undefined mixin.", name.span).into()),
         }
@@ -53,23 +55,23 @@ impl Scope {
         self.mixins.insert(s.into(), v)
     }
 
-    fn mixin_exists(&self, name: &Identifier) -> bool {
-        self.mixins.contains_key(name)
+    fn mixin_exists(&self, name: Identifier) -> bool {
+        self.mixins.contains_key(&name)
     }
 
-    fn get_fn(&self, name: &Identifier) -> Option<Function> {
-        self.functions.get(name).cloned()
+    fn get_fn(&self, name: Identifier) -> Option<Function> {
+        self.functions.get(&name).cloned()
     }
 
     pub fn insert_fn<T: Into<Identifier>>(&mut self, s: T, v: Function) -> Option<Function> {
         self.functions.insert(s.into(), v)
     }
 
-    fn fn_exists(&self, name: &Identifier) -> bool {
+    fn fn_exists(&self, name: Identifier) -> bool {
         if self.functions.is_empty() {
             return false;
         }
-        self.functions.contains_key(name)
+        self.functions.contains_key(&name)
     }
 
     fn merge(&mut self, other: Scope) {
@@ -112,7 +114,7 @@ impl Scopes {
 impl Scopes {
     pub fn insert_var(&mut self, s: Identifier, v: Spanned<Value>) -> Option<Spanned<Value>> {
         for scope in self.0.iter_mut().rev() {
-            if scope.var_exists(&s) {
+            if scope.var_exists(s) {
                 return scope.insert_var(s, v);
             }
         }
@@ -132,7 +134,7 @@ impl Scopes {
         v: Spanned<Value>,
     ) -> Option<Spanned<Value>> {
         if let Some(scope) = self.0.last_mut() {
-            if scope.var_exists(&s) {
+            if scope.var_exists(s) {
                 None
             } else {
                 scope.insert_var(s, v)
@@ -144,18 +146,18 @@ impl Scopes {
 
     pub fn get_var<'a>(
         &'a self,
-        name: Spanned<&Identifier>,
+        name: Spanned<Identifier>,
         global_scope: &'a Scope,
     ) -> SassResult<&Value> {
         for scope in self.0.iter().rev() {
-            if scope.var_exists(&name.node) {
+            if scope.var_exists(name.node) {
                 return scope.get_var(name);
             }
         }
         global_scope.get_var(name)
     }
 
-    pub fn var_exists(&self, name: &Identifier, global_scope: &Scope) -> bool {
+    pub fn var_exists(&self, name: Identifier, global_scope: &Scope) -> bool {
         for scope in &self.0 {
             if scope.var_exists(name) {
                 return true;
@@ -180,18 +182,18 @@ impl Scopes {
 
     pub fn get_mixin<'a>(
         &'a self,
-        name: Spanned<&Identifier>,
+        name: Spanned<Identifier>,
         global_scope: &'a Scope,
     ) -> SassResult<Mixin> {
         for scope in self.0.iter().rev() {
-            if scope.mixin_exists(&name.node) {
+            if scope.mixin_exists(name.node) {
                 return scope.get_mixin(name);
             }
         }
         global_scope.get_mixin(name)
     }
 
-    pub fn mixin_exists(&self, name: &Identifier, global_scope: &Scope) -> bool {
+    pub fn mixin_exists(&self, name: Identifier, global_scope: &Scope) -> bool {
         for scope in &self.0 {
             if scope.mixin_exists(name) {
                 return true;
@@ -216,18 +218,18 @@ impl Scopes {
 
     pub fn get_fn<'a>(
         &'a self,
-        name: Spanned<&Identifier>,
+        name: Spanned<Identifier>,
         global_scope: &'a Scope,
     ) -> Option<Function> {
         for scope in self.0.iter().rev() {
-            if scope.fn_exists(&name.node) {
+            if scope.fn_exists(name.node) {
                 return scope.get_fn(name.node);
             }
         }
         global_scope.get_fn(name.node)
     }
 
-    pub fn fn_exists(&self, name: &Identifier, global_scope: &Scope) -> bool {
+    pub fn fn_exists(&self, name: Identifier, global_scope: &Scope) -> bool {
         for scope in &self.0 {
             if scope.fn_exists(name) {
                 return true;
diff --git a/src/unit/mod.rs b/src/unit/mod.rs
index a9287f5..26d0b6e 100644
--- a/src/unit/mod.rs
+++ b/src/unit/mod.rs
@@ -107,6 +107,7 @@ pub(crate) enum Unit {
 
     /// Units multiplied together
     /// Boxed under the assumption that mul units are exceedingly rare
+    #[allow(clippy::box_vec)]
     Mul(Box<Vec<Unit>>),
 
     /// Units divided by each other