diff --git a/src/list.rs b/src/list.rs
index d3c05e5..dec4527 100644
--- a/src/list.rs
+++ b/src/list.rs
@@ -2,14 +2,14 @@ use crate::value::Value;
 
 /// Single-linked list
 #[derive(Debug, Default, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
-pub enum List {
-    Cons(Value, Box<Self>),
+pub enum List<'a> {
+    Cons(Value<'a>, Box<Self>),
     #[default]
     Nil,
 }
 
-impl List {
-    pub fn from_vec(vec: Vec<Value>) -> Self {
+impl<'a> List<'a> {
+    pub fn from_vec(vec: Vec<Value<'a>>) -> Self {
         vec.into_iter()
             .rev()
             .fold(Self::Nil, |list, next| Self::Cons(next, Box::new(list)))
diff --git a/src/parser.rs b/src/parser.rs
index 6a25819..4af04dc 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -7,15 +7,15 @@ pub fn read(src: &str) -> Result<Vec<Value>, Vec<Simple<Token<'_>>>> {
     parser().parse(stream_of_lexer(Token::lexer(src)))
 }
 
-fn parser<'a>() -> impl Parser<Token<'a>, Vec<Value>, Error = Simple<Token<'a>>> {
+fn parser<'a>() -> impl Parser<Token<'a>, Vec<Value<'a>>, Error = Simple<Token<'a>>> {
     recursive(|value| {
         let atom = select! {
             Token::Symbol("true") => Value::Bool(true),
             Token::Symbol("false") => Value::Bool(false),
             Token::Symbol("nil") => Value::Nil,
-            Token::Symbol(s) => Value::Symbol(s.to_owned()),
-            Token::Keyword(k) => Value::Keyword(k.to_owned()),
-            Token::String(s) => Value::String(s.to_owned()),
+            Token::Symbol(s) => Value::Symbol(s.into()),
+            Token::Keyword(k) => Value::Keyword(k.into()),
+            Token::String(s) => Value::String(s.into()),
             Token::Number(n) => Value::Number(n),
         };
 
@@ -44,7 +44,7 @@ fn parser<'a>() -> impl Parser<Token<'a>, Vec<Value>, Error = Simple<Token<'a>>>
 
         let quote = just(Token::Quote).ignore_then(value).map(|value| {
             Value::List(Box::new(List::Cons(
-                Value::Symbol("quote".to_owned()),
+                Value::Symbol("quote".into()),
                 Box::new(List::Cons(value, Box::new(List::Nil))),
             )))
         });
diff --git a/src/value.rs b/src/value.rs
index 79f66f1..d44c1a6 100644
--- a/src/value.rs
+++ b/src/value.rs
@@ -1,18 +1,21 @@
 use crate::list::List;
 use ordered_float::OrderedFloat;
-use std::collections::BTreeMap;
+use std::{borrow::Cow, collections::BTreeMap};
 
 /// A Wisp value
 #[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
-pub enum Value {
-    List(Box<List>),
+pub enum Value<'a> {
+    List(Box<List<'a>>),
     Vector(Vec<Self>),
     Map(BTreeMap<Self, Self>),
-    Symbol(String),
-    Keyword(String),
-    Function { args: Vec<Value>, body: Box<Value> },
+    Symbol(Cow<'a, str>),
+    Keyword(Cow<'a, str>),
+    Function {
+        args: Vec<Value<'a>>,
+        body: Box<Value<'a>>,
+    },
     Bool(bool),
     Number(OrderedFloat<f64>),
-    String(String),
+    String(Cow<'a, str>),
     Nil,
 }