diff --git a/src/ast/args.rs b/src/ast/args.rs
index c581d55..1233eea 100644
--- a/src/ast/args.rs
+++ b/src/ast/args.rs
@@ -81,7 +81,8 @@ impl ArgumentDeclaration {
                     } else {
                         "arguments"
                     },
-                    if num_positional == 1 { "was" } else { "were" }
+                    if num_positional == 1 { "was" } else { "were" },
+                    num_positional = num_positional,
                 ),
                 span,
             )
@@ -113,7 +114,7 @@ impl ArgumentDeclaration {
                         to_sentence(
                             unknown_names
                                 .into_iter()
-                                .map(|name| format!("${name}"))
+                                .map(|name| format!("${name}", name = name))
                                 .collect(),
                             "or"
                         )
@@ -234,7 +235,7 @@ impl ArgumentResult {
         if len > max {
             let mut err = String::with_capacity(50);
             #[allow(clippy::format_push_string)]
-            err.push_str(&format!("Only {} argument", max));
+            err.push_str(&format!("Only {max} argument", max = max));
             if max != 1 {
                 err.push('s');
             }
diff --git a/src/builtin/functions/color/hsl.rs b/src/builtin/functions/color/hsl.rs
index 43b1dd3..9920c3d 100644
--- a/src/builtin/functions/color/hsl.rs
+++ b/src/builtin/functions/color/hsl.rs
@@ -103,15 +103,15 @@ fn inner_hsl(
         let saturation = args.get_err(1, "saturation")?;
 
         if hue.is_var() || saturation.is_var() {
-            return Ok(Value::String(
+            Ok(Value::String(
                 function_string(name, &[hue, saturation], visitor, span)?,
                 QuoteKind::None,
-            ));
+            ))
         } else {
-            return Err(("Missing argument $lightness.", args.span()).into());
+            Err(("Missing argument $lightness.", args.span()).into())
         }
     } else {
-        return hsl_3_args(name, args, visitor);
+        hsl_3_args(name, args, visitor)
     }
 }
 
diff --git a/src/builtin/functions/color/rgb.rs b/src/builtin/functions/color/rgb.rs
index 23a1c01..12ba5e2 100644
--- a/src/builtin/functions/color/rgb.rs
+++ b/src/builtin/functions/color/rgb.rs
@@ -162,7 +162,8 @@ pub(crate) fn percentage_or_unitless(
         return Err((
             format!(
                 "${name}: Expected {} to have no units or \"%\".",
-                inspect_number(number, visitor.options, span)?
+                inspect_number(number, visitor.options, span)?,
+                name = name,
             ),
             span,
         )
@@ -279,7 +280,11 @@ pub(crate) fn parse_channels(
             return Ok(ParsedChannels::String(fn_string));
         } else {
             let argument = arg_names[list.len()];
-            return Err((format!("Missing element ${argument}."), span).into());
+            return Err((
+                format!("Missing element ${argument}.", argument = argument),
+                span,
+            )
+                .into());
         }
     }
 
diff --git a/src/builtin/modules/meta.rs b/src/builtin/modules/meta.rs
index 0d66175..9e86e50 100644
--- a/src/builtin/modules/meta.rs
+++ b/src/builtin/modules/meta.rs
@@ -57,7 +57,7 @@ fn load_css(mut args: ArgumentResult, visitor: &mut Visitor) -> SassResult<()> {
             if values.contains_key(&name) {
                 // todo: write test for this
                 return Err((
-                    format!("The variable {name} was configured twice."),
+                    format!("The variable {name} was configured twice.", name = name),
                     key.span,
                 )
                     .into());
diff --git a/src/evaluate/env.rs b/src/evaluate/env.rs
index 87e08a4..0fde857 100644
--- a/src/evaluate/env.rs
+++ b/src/evaluate/env.rs
@@ -263,7 +263,7 @@ impl Environment {
                 for name in (*self.scopes.global_variables()).borrow().keys() {
                     if (*module).borrow().var_exists(*name) {
                         return Err((
-                            format!("This module and the new module both define a variable named \"{name}\".")
+                            format!("This module and the new module both define a variable named \"{}\".", name = name)
                         , span).into());
                     }
                 }
diff --git a/src/evaluate/visitor.rs b/src/evaluate/visitor.rs
index 6f1bec6..bf15e55 100644
--- a/src/evaluate/visitor.rs
+++ b/src/evaluate/visitor.rs
@@ -474,7 +474,7 @@ impl<'a> Visitor<'a> {
 
         let children = supports_rule.children;
 
-        self.with_parent::<SassResult<()>>(
+        self.with_parent(
             css_supports_rule,
             true,
             |visitor| {
@@ -496,7 +496,7 @@ impl<'a> Visitor<'a> {
                         is_group_end: false,
                     };
 
-                    visitor.with_parent::<SassResult<()>>(
+                    visitor.with_parent(
                         ruleset,
                         false,
                         |visitor| {
@@ -529,7 +529,7 @@ impl<'a> Visitor<'a> {
         let env = Environment::new();
         let mut extension_store = ExtensionStore::new(self.span_before);
 
-        self.with_environment::<SassResult<()>>(env.new_closure(), |visitor| {
+        self.with_environment::<SassResult<()>, _>(env.new_closure(), |visitor| {
             let old_parent = visitor.parent;
             mem::swap(&mut visitor.extender, &mut extension_store);
             let old_style_rule = visitor.style_rule_ignoring_at_root.take();
@@ -698,7 +698,10 @@ impl<'a> Visitor<'a> {
         let Spanned { node: name, span } = config.first().unwrap();
 
         let msg = if name_in_error {
-            format!("${name} was not declared with !default in the @used module.")
+            format!(
+                "${name} was not declared with !default in the @used module.",
+                name = name
+            )
         } else {
             "This variable was not declared with !default in the @used module.".to_owned()
         };
@@ -907,6 +910,7 @@ impl<'a> Visitor<'a> {
     fn visit_content_rule(&mut self, content_rule: AstContentRule) -> SassResult<Option<Value>> {
         let span = content_rule.args.span;
         if let Some(content) = &self.env.content {
+            #[allow(mutable_borrow_reservation_conflict)]
             self.run_user_defined_callable(
                 MaybeEvaledArguments::Invocation(content_rule.args),
                 Arc::clone(content),
@@ -1008,7 +1012,7 @@ impl<'a> Visitor<'a> {
         // If we didn't exclude any rules, we don't need to use the copies we might
         // have created.
         if Some(root) == self.parent {
-            self.with_scope::<SassResult<()>>(false, true, |visitor| {
+            self.with_scope::<SassResult<()>, _>(false, true, |visitor| {
                 for stmt in at_root_rule.children {
                     let result = visitor.visit_stmt(stmt)?;
                     debug_assert!(result.is_none());
@@ -1053,7 +1057,7 @@ impl<'a> Visitor<'a> {
 
         let body = mem::take(&mut at_root_rule.children);
 
-        self.with_scope_for_at_root::<SassResult<()>>(inner_copy, &query, |visitor| {
+        self.with_scope_for_at_root::<SassResult<()>, _>(inner_copy, &query, |visitor| {
             for stmt in body {
                 let result = visitor.visit_stmt(stmt)?;
                 debug_assert!(result.is_none());
@@ -1065,11 +1069,11 @@ impl<'a> Visitor<'a> {
         Ok(None)
     }
 
-    fn with_scope_for_at_root<T>(
+    fn with_scope_for_at_root<T, F: FnOnce(&mut Self) -> T>(
         &mut self,
         new_parent_idx: Option<CssTreeIdx>,
         query: &AtRootQuery,
-        callback: impl FnOnce(&mut Self) -> T,
+        callback: F,
     ) -> T {
         let old_parent = self.parent;
         self.parent = new_parent_idx;
@@ -1272,7 +1276,7 @@ impl<'a> Visitor<'a> {
             false,
         );
 
-        self.with_parent::<SassResult<()>>(
+        self.with_parent(
             media_rule,
             true,
             |visitor| {
@@ -1298,7 +1302,7 @@ impl<'a> Visitor<'a> {
                                 is_group_end: false,
                             };
 
-                            visitor.with_parent::<SassResult<()>>(
+                            visitor.with_parent(
                                 ruleset,
                                 false,
                                 |visitor| {
@@ -1390,7 +1394,7 @@ impl<'a> Visitor<'a> {
             false,
         );
 
-        self.with_parent::<SassResult<()>>(
+        self.with_parent(
             stmt,
             true,
             |visitor| {
@@ -1412,7 +1416,7 @@ impl<'a> Visitor<'a> {
                         is_group_end: false,
                     };
 
-                    visitor.with_parent::<SassResult<()>>(
+                    visitor.with_parent(
                         style_rule,
                         false,
                         |visitor| {
@@ -1479,10 +1483,10 @@ impl<'a> Visitor<'a> {
         result
     }
 
-    fn with_environment<T>(
+    fn with_environment<T, F: FnOnce(&mut Self) -> T>(
         &mut self,
         env: Environment,
-        callback: impl FnOnce(&mut Self) -> T,
+        callback: F,
     ) -> T {
         let mut old_env = env;
         mem::swap(&mut self.env, &mut old_env);
@@ -1491,10 +1495,10 @@ impl<'a> Visitor<'a> {
         val
     }
 
-    fn add_child(
+    fn add_child<F: Fn(&CssStmt) -> bool>(
         &mut self,
         node: CssStmt,
-        through: Option<impl Fn(&CssStmt) -> bool>,
+        through: Option<F>,
     ) -> CssTreeIdx {
         if self.parent.is_none() || self.parent == Some(CssTree::ROOT) {
             return self.css_tree.add_stmt(node, self.parent);
@@ -1530,15 +1534,15 @@ impl<'a> Visitor<'a> {
         self.css_tree.add_child(node, parent)
     }
 
-    fn with_parent<T>(
+    fn with_parent<F: FnOnce(&mut Self) -> SassResult<()>, FT: Fn(&CssStmt) -> bool>(
         &mut self,
         parent: CssStmt,
         // default=true
         scope_when: bool,
-        callback: impl FnOnce(&mut Self) -> T,
+        callback: F,
         // todo: optional
-        through: impl Fn(&CssStmt) -> bool,
-    ) -> T {
+        through: FT,
+    ) -> SassResult<()> {
         let parent_idx = self.add_child(parent, Some(through));
         let old_parent = self.parent;
         self.parent = Some(parent_idx);
@@ -1547,13 +1551,13 @@ impl<'a> Visitor<'a> {
         result
     }
 
-    fn with_scope<T>(
+    fn with_scope<T, F: FnOnce(&mut Self) -> T>(
         &mut self,
         // default=false
         semi_global: bool,
         // default=true
         when: bool,
-        callback: impl FnOnce(&mut Self) -> T,
+        callback: F,
     ) -> T {
         let semi_global = semi_global && self.flags.in_semi_global_scope();
         let was_in_semi_global_scope = self.flags.in_semi_global_scope();
@@ -1624,7 +1628,7 @@ impl<'a> Visitor<'a> {
                     })
                 });
 
-                self.run_user_defined_callable::<_, ()>(
+                self.run_user_defined_callable::<_, (), _>(
                     MaybeEvaledArguments::Invocation(args),
                     mixin,
                     &env,
@@ -1767,7 +1771,7 @@ impl<'a> Visitor<'a> {
     }
 
     fn visit_while_stmt(&mut self, while_stmt: &AstWhile) -> SassResult<Option<Value>> {
-        self.with_scope::<SassResult<Option<Value>>>(true, true, |visitor| {
+        self.with_scope(true, true, |visitor| {
             let mut result = None;
 
             'outer: while visitor.visit_expr(while_stmt.condition.clone())?.is_true() {
@@ -2094,13 +2098,17 @@ impl<'a> Visitor<'a> {
         Ok(())
     }
 
-    fn run_user_defined_callable<F: UserDefinedCallable, V: fmt::Debug>(
+    fn run_user_defined_callable<
+        F: UserDefinedCallable,
+        V: fmt::Debug,
+        R: FnOnce(F, &mut Self) -> SassResult<V>,
+    >(
         &mut self,
         arguments: MaybeEvaledArguments,
         func: F,
         env: &Environment,
         span: Span,
-        run: impl FnOnce(F, &mut Self) -> SassResult<V>,
+        run: R,
     ) -> SassResult<V> {
         let mut evaluated = self.eval_maybe_args(arguments, span)?;
 
@@ -2110,7 +2118,7 @@ impl<'a> Visitor<'a> {
             name.push_str("()");
         }
 
-        self.with_environment::<SassResult<V>>(env.new_closure(), |visitor| {
+        self.with_environment(env.new_closure(), |visitor| {
             visitor.with_scope(false, true, move |visitor| {
                 func.arguments().verify(
                     evaluated.positional.len(),
@@ -2204,12 +2212,20 @@ impl<'a> Visitor<'a> {
                     evaluated
                         .named
                         .keys()
-                        .map(|key| format!("${key}"))
+                        .map(|key| format!("${key}", key = key))
                         .collect(),
                     "or",
                 );
 
-                Err((format!("No {argument_word} named {argument_names}."), span).into())
+                Err((
+                    format!(
+                        "No {argument_word} named {argument_names}.",
+                        argument_word = argument_word,
+                        argument_names = argument_names
+                    ),
+                    span,
+                )
+                    .into())
             })
         })
     }
@@ -2762,7 +2778,7 @@ impl<'a> Visitor<'a> {
                 body: Vec::new(),
             });
 
-            self.with_parent::<SassResult<()>>(
+            self.with_parent(
                 keyframes_ruleset,
                 true,
                 |visitor| {
@@ -2813,7 +2829,7 @@ impl<'a> Visitor<'a> {
         let old_style_rule_ignoring_at_root = self.style_rule_ignoring_at_root.take();
         self.style_rule_ignoring_at_root = Some(selector);
 
-        self.with_parent::<SassResult<()>>(
+        self.with_parent(
             rule,
             true,
             |visitor| {
@@ -2910,7 +2926,7 @@ impl<'a> Visitor<'a> {
         if !children.is_empty() {
             let old_declaration_name = self.declaration_name.take();
             self.declaration_name = Some(name);
-            self.with_scope::<SassResult<()>>(false, true, |visitor| {
+            self.with_scope::<SassResult<()>, _>(false, true, |visitor| {
                 for stmt in children {
                     let result = visitor.visit_stmt(stmt)?;
                     debug_assert!(result.is_none());
diff --git a/src/lib.rs b/src/lib.rs
index ea67dab..a851e56 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -64,6 +64,8 @@ grass input.scss
     clippy::wildcard_imports,
     clippy::comparison_chain,
     clippy::bool_to_int_with_if,
+
+    unknown_lints,
 )]
 
 use std::path::Path;
diff --git a/src/main.rs b/src/main.rs
index 63636c3..3546d38 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -205,7 +205,7 @@ fn main() -> std::io::Result<()> {
             .open(path)?;
         &mut file_write
     } else {
-        stdout_write = stdout().lock();
+        stdout_write = stdout();
         &mut stdout_write
     };
 
diff --git a/src/parse/base.rs b/src/parse/base.rs
index dc37a3f..17796d6 100644
--- a/src/parse/base.rs
+++ b/src/parse/base.rs
@@ -330,7 +330,11 @@ pub(crate) trait BaseParser<'a> {
         }
 
         if !found_matching_quote {
-            return Err((format!("Expected {quote}."), self.toks().current_span()).into());
+            return Err((
+                format!("Expected {quote}.", quote = quote),
+                self.toks().current_span(),
+            )
+                .into());
         }
 
         Ok(buffer)
diff --git a/src/parse/mod.rs b/src/parse/mod.rs
index 90a0a64..ae9cb92 100644
--- a/src/parse/mod.rs
+++ b/src/parse/mod.rs
@@ -20,6 +20,7 @@ mod stylesheet;
 mod value;
 
 #[derive(Debug, Clone)]
+#[allow(clippy::large_enum_variant)]
 pub(crate) enum DeclarationOrBuffer {
     Stmt(AstStmt),
     Buffer(Interpolation),
diff --git a/src/parse/sass.rs b/src/parse/sass.rs
index 88ae30c..905cd94 100644
--- a/src/parse/sass.rs
+++ b/src/parse/sass.rs
@@ -511,7 +511,10 @@ impl<'a> SassParser<'a> {
 
             if child_indent != indentation {
                 return Err((
-                    format!("Inconsistent indentation, expected {child_indent} spaces."),
+                    format!(
+                        "Inconsistent indentation, expected {child_indent} spaces.",
+                        child_indent = child_indent
+                    ),
                     self.toks.current_span(),
                 )
                     .into());
diff --git a/src/parse/stylesheet.rs b/src/parse/stylesheet.rs
index 391e5b9..8e6808e 100644
--- a/src/parse/stylesheet.rs
+++ b/src/parse/stylesheet.rs
@@ -1044,7 +1044,11 @@ pub(crate) trait StylesheetParser<'a>: BaseParser<'a> + Sized {
         }
 
         if !found_match {
-            return Err((format!("Expected {quote}."), self.toks().current_span()).into());
+            return Err((
+                format!("Expected {quote}.", quote = quote),
+                self.toks().current_span(),
+            )
+                .into());
         }
 
         Ok(Spanned {
@@ -1547,7 +1551,10 @@ pub(crate) trait StylesheetParser<'a>: BaseParser<'a> + Sized {
             (Ok(i), true) => Ok(Some(i)),
             _ => {
                 Err((
-                    format!("The default namespace \"{namespace}\" is not a valid Sass identifier.\n\nRecommendation: add an \"as\" clause to define an explicit namespace."),
+                    format!(
+                        "The default namespace \"{namespace}\" is not a valid Sass identifier.\n\nRecommendation: add an \"as\" clause to define an explicit namespace.", 
+                        namespace = namespace
+                    ),
                     self.toks_mut().span_from(start)
                 ).into())
             }
diff --git a/src/utils/mod.rs b/src/utils/mod.rs
index caa302c..df49572 100644
--- a/src/utils/mod.rs
+++ b/src/utils/mod.rs
@@ -92,6 +92,7 @@ pub(crate) fn to_sentence<T: Into<String>>(mut elems: Vec<T>, conjunction: &'sta
             .map(Into::into)
             .collect::<Vec<_>>()
             .join(", "),
-        last.into()
+        last.into(),
+        conjunction = conjunction,
     )
 }
diff --git a/src/value/calculation.rs b/src/value/calculation.rs
index b086376..c938b3c 100644
--- a/src/value/calculation.rs
+++ b/src/value/calculation.rs
@@ -245,7 +245,9 @@ impl SassCalculation {
         Err((
             format!(
                 "{len} arguments required, but only {} {was_or_were} passed.",
-                args.len()
+                args.len(),
+                len = len,
+                was_or_were = was_or_were,
             ),
             span,
         )
diff --git a/src/value/mod.rs b/src/value/mod.rs
index e4ebd35..ba85034 100644
--- a/src/value/mod.rs
+++ b/src/value/mod.rs
@@ -228,7 +228,11 @@ impl Value {
         match self {
             Value::Dimension(n) => Ok(n),
             _ => Err((
-                format!("${name}: {} is not a number.", self.inspect(span)?),
+                format!(
+                    "${name}: {} is not a number.",
+                    self.inspect(span)?,
+                    name = name,
+                ),
                 span,
             )
                 .into()),
@@ -239,7 +243,11 @@ impl Value {
         match self {
             Value::Color(c) => Ok(*c),
             _ => Err((
-                format!("${name}: {} is not a color.", self.inspect(span)?),
+                format!(
+                    "${name}: {} is not a color.",
+                    self.inspect(span)?,
+                    name = name,
+                ),
                 span,
             )
                 .into()),
diff --git a/src/value/number.rs b/src/value/number.rs
index 349a142..6dee36a 100644
--- a/src/value/number.rs
+++ b/src/value/number.rs
@@ -121,7 +121,11 @@ impl Number {
         match fuzzy_as_int(self.0) {
             Some(i) => Ok(i),
             None => Err((
-                format!("${name}: {} is not an int.", self.to_string(false)),
+                format!(
+                    "${name}: {} is not an int.",
+                    self.to_string(false),
+                    name = name,
+                ),
                 span,
             )
                 .into()),
diff --git a/src/value/sass_number.rs b/src/value/sass_number.rs
index b18f966..f31378e 100644
--- a/src/value/sass_number.rs
+++ b/src/value/sass_number.rs
@@ -136,7 +136,8 @@ impl SassNumber {
             Err((
                 format!(
                     "${name}: Expected {} to have no units.",
-                    inspect_number(self, &Options::default(), span)?
+                    inspect_number(self, &Options::default(), span)?,
+                    name = name,
                 ),
                 span,
             )
@@ -151,7 +152,9 @@ impl SassNumber {
             Err((
                 format!(
                     "${name}: Expected {} to have unit \"{unit}\".",
-                    inspect_number(self, &Options::default(), span)?
+                    inspect_number(self, &Options::default(), span)?,
+                    name = name,
+                    unit = unit,
                 ),
                 span,
             )
diff --git a/tests/imports.rs b/tests/imports.rs
index 4b6b852..fa40860 100644
--- a/tests/imports.rs
+++ b/tests/imports.rs
@@ -448,7 +448,6 @@ fn chained_imports_in_directory() {
         &grass::from_string(input.to_string(), &grass::Options::default()).expect(input)
     );
 }
-
 error!(
     // note: dart-sass error is "expected more input."
     missing_input_after_import,