diff --git a/grass_internal/src/ast/expr.rs b/grass_internal/src/ast/expr.rs
index df95ad2..84ec01e 100644
--- a/grass_internal/src/ast/expr.rs
+++ b/grass_internal/src/ast/expr.rs
@@ -26,14 +26,14 @@ pub(crate) struct ListExpr {
 pub(crate) struct FunctionCallExpr {
     pub namespace: Option<Spanned<Identifier>>,
     pub name: Identifier,
-    pub arguments: Box<ArgumentInvocation>,
+    pub arguments: Arc<ArgumentInvocation>,
     pub span: Span,
 }
 
 #[derive(Debug, Clone)]
 pub(crate) struct InterpolatedFunction {
     pub name: Interpolation,
-    pub arguments: Box<ArgumentInvocation>,
+    pub arguments: ArgumentInvocation,
     pub span: Span,
 }
 
@@ -61,7 +61,7 @@ pub(crate) enum AstExpr {
     Color(Arc<Color>),
     FunctionCall(FunctionCallExpr),
     If(Arc<Ternary>),
-    InterpolatedFunction(InterpolatedFunction),
+    InterpolatedFunction(Arc<InterpolatedFunction>),
     List(ListExpr),
     Map(AstSassMap),
     Null,
diff --git a/grass_internal/src/evaluate/visitor.rs b/grass_internal/src/evaluate/visitor.rs
index 34e8cd0..0ffee6a 100644
--- a/grass_internal/src/evaluate/visitor.rs
+++ b/grass_internal/src/evaluate/visitor.rs
@@ -2360,7 +2360,8 @@ impl<'a> Visitor<'a> {
 
         let old_in_function = self.flags.in_function();
         self.flags.set(ContextFlags::IN_FUNCTION, true);
-        let value = self.run_function_callable(func, *func_call.arguments, func_call.span)?;
+        let value =
+            self.run_function_callable(func, (*func_call.arguments).clone(), func_call.span)?;
         self.flags.set(ContextFlags::IN_FUNCTION, old_in_function);
 
         Ok(value)
@@ -2381,7 +2382,7 @@ impl<'a> Visitor<'a> {
         let mut buffer = format!("{}(", fn_name);
 
         let mut first = true;
-        for arg in args.positional {
+        for arg in args.positional.clone() {
             if first {
                 first = false;
             } else {
@@ -2391,7 +2392,7 @@ impl<'a> Visitor<'a> {
             buffer.push_str(&evaluated);
         }
 
-        if let Some(rest_arg) = args.rest {
+        if let Some(rest_arg) = args.rest.clone() {
             let rest = self.visit_expr(rest_arg)?;
             if !first {
                 buffer.push_str(", ");
@@ -2421,15 +2422,13 @@ impl<'a> Visitor<'a> {
             }),
             AstExpr::List(list) => self.visit_list_expr(list)?,
             AstExpr::String(StringExpr(text, quote), ..) => self.visit_string(text, quote)?,
-            AstExpr::BinaryOp(binop) => {
-                self.visit_bin_op(
-                    binop.lhs.clone(),
-                    binop.op,
-                    binop.rhs.clone(),
-                    binop.allows_slash,
-                    binop.span,
-                )?
-            }
+            AstExpr::BinaryOp(binop) => self.visit_bin_op(
+                binop.lhs.clone(),
+                binop.op,
+                binop.rhs.clone(),
+                binop.allows_slash,
+                binop.span,
+            )?,
             AstExpr::True => Value::True,
             AstExpr::False => Value::False,
             AstExpr::Calculation { name, args } => {
@@ -2437,7 +2436,9 @@ impl<'a> Visitor<'a> {
             }
             AstExpr::FunctionCall(func_call) => self.visit_function_call_expr(func_call)?,
             AstExpr::If(if_expr) => self.visit_ternary((*if_expr).clone())?,
-            AstExpr::InterpolatedFunction(func) => self.visit_interpolated_func_expr(func)?,
+            AstExpr::InterpolatedFunction(func) => {
+                self.visit_interpolated_func_expr((*func).clone())?
+            }
             AstExpr::Map(map) => self.visit_map(map)?,
             AstExpr::Null => Value::Null,
             AstExpr::Paren(expr) => self.visit_expr((*expr).clone())?,
@@ -2477,17 +2478,15 @@ impl<'a> Visitor<'a> {
                 debug_assert!(string_expr.1 == QuoteKind::None);
                 CalculationArg::Interpolation(self.perform_interpolation(string_expr.0, false)?)
             }
-            AstExpr::BinaryOp(binop) => {
-                SassCalculation::operate_internal(
-                    binop.op,
-                    self.visit_calculation_value(binop.lhs.clone(), in_min_or_max, span)?,
-                    self.visit_calculation_value(binop.rhs.clone(), in_min_or_max, span)?,
-                    in_min_or_max,
-                    !self.flags.in_supports_declaration(),
-                    self.options,
-                    span,
-                )?
-            }
+            AstExpr::BinaryOp(binop) => SassCalculation::operate_internal(
+                binop.op,
+                self.visit_calculation_value(binop.lhs.clone(), in_min_or_max, span)?,
+                self.visit_calculation_value(binop.rhs.clone(), in_min_or_max, span)?,
+                in_min_or_max,
+                !self.flags.in_supports_declaration(),
+                self.options,
+                span,
+            )?,
             AstExpr::Number { .. }
             | AstExpr::Calculation { .. }
             | AstExpr::Variable { .. }
diff --git a/grass_internal/src/parse/css.rs b/grass_internal/src/parse/css.rs
index 0fa68e1..22a2248 100644
--- a/grass_internal/src/parse/css.rs
+++ b/grass_internal/src/parse/css.rs
@@ -1,4 +1,4 @@
-use std::{collections::BTreeMap, path::Path};
+use std::{collections::BTreeMap, path::Path, sync::Arc};
 
 use codemap::{CodeMap, Span, Spanned};
 
@@ -203,17 +203,17 @@ impl<'a> CssParser<'a> {
             return Err(("This function isn't allowed in plain CSS.", span).into());
         }
 
-        Ok(AstExpr::InterpolatedFunction(InterpolatedFunction {
+        Ok(AstExpr::InterpolatedFunction(Arc::new(InterpolatedFunction {
             name: identifier,
-            arguments: Box::new(ArgumentInvocation {
+            arguments: ArgumentInvocation {
                 positional: arguments,
                 named: BTreeMap::new(),
                 rest: None,
                 keyword_rest: None,
                 span: self.toks.span_from(before_args),
-            }),
+            },
             span,
-        })
+        }))
         .span(span))
     }
 }
diff --git a/grass_internal/src/parse/stylesheet.rs b/grass_internal/src/parse/stylesheet.rs
index 5e20a77..fe62434 100644
--- a/grass_internal/src/parse/stylesheet.rs
+++ b/grass_internal/src/parse/stylesheet.rs
@@ -3,7 +3,8 @@ use std::{
     collections::{BTreeMap, HashSet},
     ffi::OsString,
     mem,
-    path::{Path, PathBuf}, sync::Arc,
+    path::{Path, PathBuf},
+    sync::Arc,
 };
 
 use codemap::{CodeMap, Span, Spanned};
@@ -840,11 +841,11 @@ pub(crate) trait StylesheetParser<'a>: BaseParser<'a> + Sized {
                 StringExpr(contents, QuoteKind::None),
                 self.toks_mut().span_from(start),
             ),
-            None => AstExpr::InterpolatedFunction(InterpolatedFunction {
+            None => AstExpr::InterpolatedFunction(Arc::new(InterpolatedFunction {
                 name: Interpolation::new_plain("url".to_owned()),
-                arguments: Box::new(self.parse_argument_invocation(false, false)?),
+                arguments: self.parse_argument_invocation(false, false)?,
                 span: self.toks_mut().span_from(start),
-            }),
+            })),
         })
     }
 
diff --git a/grass_internal/src/parse/value.rs b/grass_internal/src/parse/value.rs
index 866369a..307dc20 100644
--- a/grass_internal/src/parse/value.rs
+++ b/grass_internal/src/parse/value.rs
@@ -1228,17 +1228,17 @@ impl<'a, 'c, P: StylesheetParser<'a>> ValueParser<'a, 'c, P> {
                     Ok(AstExpr::FunctionCall(FunctionCallExpr {
                         namespace: None,
                         name: Identifier::from(plain),
-                        arguments: Box::new(arguments),
+                        arguments: Arc::new(arguments),
                         span: parser.toks_mut().span_from(start),
                     })
                     .span(parser.toks_mut().span_from(start)))
                 } else {
                     let arguments = parser.parse_argument_invocation(false, false)?;
-                    Ok(AstExpr::InterpolatedFunction(InterpolatedFunction {
+                    Ok(AstExpr::InterpolatedFunction(Arc::new(InterpolatedFunction {
                         name: identifier,
-                        arguments: Box::new(arguments),
+                        arguments,
                         span: parser.toks_mut().span_from(start),
-                    })
+                    }))
                     .span(parser.toks_mut().span_from(start)))
                 }
             }
@@ -1286,7 +1286,7 @@ impl<'a, 'c, P: StylesheetParser<'a>> ValueParser<'a, 'c, P> {
         Ok(AstExpr::FunctionCall(FunctionCallExpr {
             namespace: Some(namespace),
             name: Identifier::from(name),
-            arguments: Box::new(args),
+            arguments: Arc::new(args),
             span,
         })
         .span(span))
@@ -1575,7 +1575,7 @@ impl<'a, 'c, P: StylesheetParser<'a>> ValueParser<'a, 'c, P> {
                     Ok(AstExpr::FunctionCall(FunctionCallExpr {
                         namespace: None,
                         name: Identifier::from(ident),
-                        arguments: Box::new(parser.parse_argument_invocation(false, false)?),
+                        arguments: Arc::new(parser.parse_argument_invocation(false, false)?),
                         span: parser.toks_mut().span_from(start),
                     })
                     .span(parser.toks_mut().span_from(start)))
diff --git a/grass_internal/src/unit/mod.rs b/grass_internal/src/unit/mod.rs
index 970fa3c..7e38e55 100644
--- a/grass_internal/src/unit/mod.rs
+++ b/grass_internal/src/unit/mod.rs
@@ -1,4 +1,4 @@
-use std::fmt;
+use std::{fmt, sync::Arc};
 
 use crate::interner::InternedString;
 
@@ -100,7 +100,7 @@ pub(crate) enum Unit {
     /// Unspecified unit
     None,
 
-    Complex(Box<ComplexUnit>),
+    Complex(Arc<ComplexUnit>),
 }
 
 #[derive(Clone, Debug, PartialEq, Eq, Hash)]
@@ -141,13 +141,13 @@ impl Unit {
         } else if denom.is_empty() && numer.len() == 1 {
             numer.pop().unwrap()
         } else {
-            Unit::Complex(Box::new(ComplexUnit { numer, denom }))
+            Unit::Complex(Arc::new(ComplexUnit { numer, denom }))
         }
     }
 
     pub fn numer_and_denom(self) -> (Vec<Unit>, Vec<Unit>) {
         match self {
-            Self::Complex(complex) => (complex.numer, complex.denom),
+            Self::Complex(complex) => (complex.numer.clone(), complex.denom.clone()),
             Self::None => (Vec::new(), Vec::new()),
             v => (vec![v], Vec::new()),
         }
diff --git a/grass_internal/src/value/mod.rs b/grass_internal/src/value/mod.rs
index 6de38bc..2a62006 100644
--- a/grass_internal/src/value/mod.rs
+++ b/grass_internal/src/value/mod.rs
@@ -129,7 +129,7 @@ impl Value {
         span: Span,
     ) -> SassResult<Self> {
         let mut number = self.assert_number(span)?;
-        number.as_slash = Some(Box::new((numerator, denom)));
+        number.as_slash = Some(Arc::new((numerator, denom)));
         Ok(Value::Dimension(number))
     }
 
@@ -194,7 +194,7 @@ impl Value {
             Value::Null => true,
             Value::String(i, QuoteKind::None) if i.is_empty() => true,
             Value::List(_, _, Brackets::Bracketed) => false,
-            Value::List(v, ..) => v.iter().map(Value::is_blank).all(|f| f),
+            Value::List(v, ..) => v.iter().all(Value::is_blank),
             Value::ArgList(v, ..) => v.is_blank(),
             _ => false,
         }
@@ -258,7 +258,7 @@ impl Value {
         }
     }
 
-    pub fn as_slash(&self) -> Option<Box<(SassNumber, SassNumber)>> {
+    pub fn as_slash(&self) -> Option<Arc<(SassNumber, SassNumber)>> {
         match self {
             Value::Dimension(SassNumber { as_slash, .. }) => as_slash.clone(),
             _ => None,
diff --git a/grass_internal/src/value/sass_number.rs b/grass_internal/src/value/sass_number.rs
index 8085270..da8f4a2 100644
--- a/grass_internal/src/value/sass_number.rs
+++ b/grass_internal/src/value/sass_number.rs
@@ -1,4 +1,7 @@
-use std::ops::{Add, Div, Mul, Sub};
+use std::{
+    ops::{Add, Div, Mul, Sub},
+    sync::Arc,
+};
 
 use codemap::Span;
 
@@ -11,12 +14,11 @@ use crate::{
 
 use super::Number;
 
-// todo: is as_slash included in eq
 #[derive(Debug, Clone)]
 pub(crate) struct SassNumber {
     pub num: Number,
     pub unit: Unit,
-    pub as_slash: Option<Box<(Self, Self)>>,
+    pub as_slash: Option<Arc<(Self, Self)>>,
 }
 
 pub(crate) fn conversion_factor(from: &Unit, to: &Unit) -> Option<f64> {