diff --git a/ruff_cli/src/diagnostics.rs b/ruff_cli/src/diagnostics.rs
index 14d39e8170..616f262c6e 100644
--- a/ruff_cli/src/diagnostics.rs
+++ b/ruff_cli/src/diagnostics.rs
@@ -79,10 +79,10 @@ pub fn lint_path(
         {
             if fixed > 0 {
                 if matches!(autofix, fix::FixMode::Apply) {
-                    write(path, transformed)?;
+                    write(path, transformed.as_bytes())?;
                 } else if matches!(autofix, fix::FixMode::Diff) {
                     let mut stdout = io::stdout().lock();
-                    TextDiff::from_lines(&contents, &transformed)
+                    TextDiff::from_lines(contents.as_str(), &transformed)
                         .unified_diff()
                         .header(&fs::relativize_path(path), &fs::relativize_path(path))
                         .to_writer(&mut stdout)?;
diff --git a/src/linter.rs b/src/linter.rs
index 8829fd957d..e7f0066bd4 100644
--- a/src/linter.rs
+++ b/src/linter.rs
@@ -1,3 +1,4 @@
+use std::borrow::Cow;
 use std::path::Path;
 
 use anyhow::{anyhow, Result};
@@ -314,13 +315,13 @@ pub fn lint_only(
 
 /// Generate `Diagnostic`s from source code content, iteratively autofixing
 /// until stable.
-pub fn lint_fix(
-    contents: &str,
+pub fn lint_fix<'a>(
+    contents: &'a str,
     path: &Path,
     package: Option<&Path>,
     settings: &Settings,
-) -> Result<(LinterResult<Vec<Message>>, String, usize)> {
-    let mut transformed = contents.to_string();
+) -> Result<(LinterResult<Vec<Message>>, Cow<'a, str>, usize)> {
+    let mut transformed = Cow::Borrowed(contents);
 
     // Track the number of fixed errors across iterations.
     let mut fixed = 0;
@@ -397,7 +398,7 @@ This indicates a bug in `{}`. If you could open an issue at:
                 fixed += applied;
 
                 // Store the fixed contents.
-                transformed = fixed_contents.to_string();
+                transformed = Cow::Owned(fixed_contents);
 
                 // Increment the iteration count.
                 iterations += 1;