diff --git a/src/atrule/mod.rs b/src/atrule/mod.rs
index a8e9841..572186e 100644
--- a/src/atrule/mod.rs
+++ b/src/atrule/mod.rs
@@ -37,7 +37,7 @@ impl AtRule {
         rule: &AtRuleKind,
         pos: Pos,
         toks: &mut Peekable<I>,
-        scope: &Scope,
+        scope: &mut Scope,
         super_selector: &Selector,
     ) -> SassResult<AtRule> {
         devour_whitespace(toks);
@@ -71,7 +71,7 @@ impl AtRule {
                 AtRule::Mixin(name, Box::new(mixin))
             }
             AtRuleKind::Function => {
-                let (name, func) = Function::decl_from_tokens(toks, scope)?;
+                let (name, func) = Function::decl_from_tokens(toks, scope.clone())?;
                 AtRule::Function(name, Box::new(func))
             }
             AtRuleKind::Return => {
@@ -176,13 +176,12 @@ impl AtRule {
 
                 devour_whitespace_or_comment(toks);
 
-                let mut scope = scope.clone();
                 if from < to {
                     for i in from..(to + through) {
                         scope.insert_var(&var, Value::Dimension(Number::from(i), Unit::None))?;
                         stmts.extend(eat_stmts(
                             &mut body.clone().into_iter().peekable(),
-                            &scope,
+                            scope,
                             super_selector,
                         )?);
                     }
@@ -191,7 +190,7 @@ impl AtRule {
                         scope.insert_var(&var, Value::Dimension(Number::from(i), Unit::None))?;
                         stmts.extend(eat_stmts(
                             &mut body.clone().into_iter().peekable(),
-                            &scope,
+                            scope,
                             super_selector,
                         )?);
                     }
diff --git a/src/atrule/parse.rs b/src/atrule/parse.rs
index 3328c5a..1fd03d4 100644
--- a/src/atrule/parse.rs
+++ b/src/atrule/parse.rs
@@ -7,12 +7,11 @@ use crate::{eat_expr, Expr, RuleSet, Stmt, Token};
 
 pub(crate) fn eat_stmts<I: Iterator<Item = Token>>(
     toks: &mut Peekable<I>,
-    scope: &Scope,
+    scope: &mut Scope,
     super_selector: &Selector,
 ) -> SassResult<Vec<Stmt>> {
     let mut stmts = Vec::new();
-    let mut scope = scope.clone();
-    while let Some(expr) = eat_expr(toks, &scope, super_selector)? {
+    while let Some(expr) = eat_expr(toks, scope, super_selector)? {
         match expr {
             Expr::AtRule(a) => stmts.push(Stmt::AtRule(a)),
             Expr::Style(s) => stmts.push(Stmt::Style(s)),
@@ -22,7 +21,7 @@ pub(crate) fn eat_stmts<I: Iterator<Item = Token>>(
                 todo!()
             }
             Expr::Selector(selector) => {
-                let rules = eat_stmts(toks, &scope, &super_selector.zip(&selector))?;
+                let rules = eat_stmts(toks, scope, &super_selector.zip(&selector))?;
                 stmts.push(Stmt::RuleSet(RuleSet {
                     super_selector: super_selector.clone(),
                     selector,
diff --git a/src/atrule/unknown.rs b/src/atrule/unknown.rs
index 997dcf7..f542ec6 100644
--- a/src/atrule/unknown.rs
+++ b/src/atrule/unknown.rs
@@ -19,7 +19,7 @@ impl UnknownAtRule {
     pub fn from_tokens<I: Iterator<Item = Token>>(
         toks: &mut Peekable<I>,
         name: &str,
-        scope: &Scope,
+        scope: &mut Scope,
         super_selector: &Selector,
     ) -> SassResult<UnknownAtRule> {
         let mut params = String::new();
diff --git a/src/function.rs b/src/function.rs
index cf1f325..8b1a86e 100644
--- a/src/function.rs
+++ b/src/function.rs
@@ -23,7 +23,7 @@ impl Function {
 
     pub fn decl_from_tokens<I: Iterator<Item = Token>>(
         toks: &mut Peekable<I>,
-        scope: &Scope,
+        mut scope: Scope,
     ) -> SassResult<(String, Function)> {
         let Token { kind, .. } = toks
             .next()
@@ -38,7 +38,7 @@ impl Function {
             Some(Token {
                 kind: TokenKind::Symbol(Symbol::OpenParen),
                 ..
-            }) => eat_func_args(toks, scope)?,
+            }) => eat_func_args(toks, &scope)?,
             _ => return Err("expected \"(\".".into()),
         };
 
@@ -52,7 +52,7 @@ impl Function {
                         rule,
                         tok.pos,
                         toks,
-                        scope,
+                        &mut scope,
                         &Selector::new(),
                     )?),
                     TokenKind::Symbol(Symbol::CloseCurlyBrace) => nesting -= 1,
diff --git a/src/lib.rs b/src/lib.rs
index 2e7c686..f88c05d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -460,7 +460,7 @@ impl<'a> StyleSheetParser<'a> {
                         pos,
                     }) = self.lexer.next()
                     {
-                        match AtRule::from_tokens(rule, pos, &mut self.lexer, &self.global_scope, &Selector::new())? {
+                        match AtRule::from_tokens(rule, pos, &mut self.lexer, &mut self.global_scope, &Selector::new())? {
                             AtRule::Mixin(name, mixin) => {
                                 self.global_scope.insert_mixin(&name, *mixin);
                             }
@@ -542,7 +542,7 @@ impl<'a> StyleSheetParser<'a> {
 
 pub(crate) fn eat_expr<I: Iterator<Item = Token>>(
     toks: &mut Peekable<I>,
-    scope: &Scope,
+    scope: &mut Scope,
     super_selector: &Selector,
 ) -> SassResult<Option<Expr>> {
     let mut values = Vec::with_capacity(5);
diff --git a/src/mixin.rs b/src/mixin.rs
index abcc0ce..ab89a0f 100644
--- a/src/mixin.rs
+++ b/src/mixin.rs
@@ -92,7 +92,7 @@ impl Mixin {
 
     fn eval(&mut self, super_selector: &Selector) -> SassResult<Vec<Stmt>> {
         let mut stmts = Vec::new();
-        while let Some(expr) = eat_expr(&mut self.body, &self.scope, super_selector)? {
+        while let Some(expr) = eat_expr(&mut self.body, &mut self.scope, super_selector)? {
             match expr {
                 Expr::AtRule(a) => stmts.push(Stmt::AtRule(a)),
                 Expr::Style(s) => stmts.push(Stmt::Style(s)),
diff --git a/tests/for.rs b/tests/for.rs
index 8e4041d..f2ad251 100644
--- a/tests/for.rs
+++ b/tests/for.rs
@@ -38,3 +38,8 @@ test!(
     "a {\n  @for $i from 1 to 3 {\n    color: $i;\n  }\n}\n",
     "a {\n  color: 1;\n  color: 2;\n}\n"
 );
+test!(
+    scope,
+    "a {\n  $a: red;\n  @for $i from 1 to 3 {\n    $a: blue;\n  }\n  color: $a;\n}\n",
+    "a {\n  color: blue;\n}\n"
+);