diff --git a/stack-core/src/chain.rs b/stack-core/src/chain.rs
index b4c15cfc..2ee8823a 100644
--- a/stack-core/src/chain.rs
+++ b/stack-core/src/chain.rs
@@ -1,24 +1,24 @@
 use core::cell::RefCell;
-use std::{borrow::BorrowMut, rc::Rc};
+use std::{borrow::BorrowMut, sync::Arc};
 
 #[derive(Debug, PartialEq, Clone)]
 pub struct Chain<T> {
-  value: Rc<RefCell<T>>,
-  child: Option<Rc<RefCell<Chain<T>>>>,
+  value: Arc<RefCell<T>>,
+  child: Option<Arc<RefCell<Chain<T>>>>,
   root: bool,
 }
 
 impl<T> Chain<T> {
   pub fn new(value: T) -> Self {
     Self {
-      value: Rc::new(RefCell::new(value)),
+      value: Arc::new(RefCell::new(value)),
       child: None,
       root: true,
     }
   }
 
-  pub fn link(&mut self) -> Rc<RefCell<Self>> {
-    let child = Rc::new(RefCell::new(Self {
+  pub fn link(&mut self) -> Arc<RefCell<Self>> {
+    let child = Arc::new(RefCell::new(Self {
       value: self.value.clone(),
       child: None,
       root: false,
@@ -28,7 +28,7 @@ impl<T> Chain<T> {
     child
   }
 
-  pub fn root(&self) -> Rc<RefCell<T>> {
+  pub fn root(&self) -> Arc<RefCell<T>> {
     self.value.clone()
   }
 
@@ -45,7 +45,7 @@ where
     self.value.borrow().clone()
   }
 
-  fn unlink_with_rc(&mut self, value: Rc<RefCell<T>>, new_root: bool) {
+  fn unlink_with_rc(&mut self, value: Arc<RefCell<T>>, new_root: bool) {
     let mut new_root = new_root;
 
     if new_root {
@@ -61,7 +61,7 @@ where
   }
 
   pub fn unlink_with(&mut self, val: T) {
-    self.unlink_with_rc(Rc::new(RefCell::new(val)), true);
+    self.unlink_with_rc(Arc::new(RefCell::new(val)), true);
   }
 
   pub fn set(&mut self, val: T) {
diff --git a/stack-core/src/context.rs b/stack-core/src/context.rs
index 6da9627c..0b0d090f 100644
--- a/stack-core/src/context.rs
+++ b/stack-core/src/context.rs
@@ -1,4 +1,4 @@
-use std::{cell::RefCell, collections::HashMap, rc::Rc};
+use std::{cell::RefCell, collections::HashMap, sync::Arc};
 
 use crate::{
   chain::Chain,
@@ -141,7 +141,7 @@ impl Context {
   #[inline]
   pub fn scope_items(
     &self,
-  ) -> impl Iterator<Item = (&Symbol, &Rc<RefCell<Chain<Option<Expr>>>>)> {
+  ) -> impl Iterator<Item = (&Symbol, &Arc<RefCell<Chain<Option<Expr>>>>)> {
     self.scopes.last().items.iter()
   }
 
diff --git a/stack-core/src/scope.rs b/stack-core/src/scope.rs
index b96ca3ad..af123919 100644
--- a/stack-core/src/scope.rs
+++ b/stack-core/src/scope.rs
@@ -1,9 +1,9 @@
 use core::fmt;
-use std::{cell::RefCell, collections::HashMap, fmt::Formatter, rc::Rc};
+use std::{cell::RefCell, collections::HashMap, fmt::Formatter, sync::Arc};
 
 use crate::{chain::Chain, expr::FnIdent, prelude::*};
 
-pub type Val = Rc<RefCell<Chain<Option<Expr>>>>;
+pub type Val = Arc<RefCell<Chain<Option<Expr>>>>;
 
 #[derive(Default, PartialEq)]
 pub struct Scope {
@@ -50,14 +50,14 @@ impl Scope {
         }
       }
     } else {
-      let val = Rc::new(RefCell::new(Chain::new(Some(item))));
+      let val = Arc::new(RefCell::new(Chain::new(Some(item))));
       self.items.insert(name, val);
     }
   }
 
   pub fn reserve(&mut self, name: Symbol) {
     if self.items.get(&name).is_none() {
-      let val = Rc::new(RefCell::new(Chain::new(None)));
+      let val = Arc::new(RefCell::new(Chain::new(None)));
       self.items.insert(name, val);
     }
   }
diff --git a/stack-core/src/source.rs b/stack-core/src/source.rs
index 2dc09bf9..2aca9e9d 100644
--- a/stack-core/src/source.rs
+++ b/stack-core/src/source.rs
@@ -1,5 +1,5 @@
 use core::{fmt, num::NonZeroUsize};
-use std::{fs, io, path::Path, rc::Rc};
+use std::{fs, io, path::Path, sync::Arc};
 
 use unicode_segmentation::UnicodeSegmentation;
 
@@ -7,7 +7,7 @@ use unicode_segmentation::UnicodeSegmentation;
 ///
 /// This internally stores an [`Rc`], hence it is *cheap* to clone.
 #[derive(Debug, Clone, PartialEq, Eq)]
-pub struct Source(Rc<SourceInner>);
+pub struct Source(Arc<SourceInner>);
 
 impl Source {
   /// Creates a new [`Source`].
@@ -27,7 +27,7 @@ impl Source {
       )
       .collect::<Vec<_>>();
 
-    Self(Rc::new(SourceInner {
+    Self(Arc::new(SourceInner {
       name,
       source,
       line_starts,