diff --git a/crates/ruff_cli/src/args.rs b/crates/ruff_cli/src/args.rs
index 813c34980c..6236f4a2e4 100644
--- a/crates/ruff_cli/src/args.rs
+++ b/crates/ruff_cli/src/args.rs
@@ -80,7 +80,7 @@ pub struct CheckArgs {
     #[clap(long, overrides_with("show_fixes"), hide = true)]
     no_show_fixes: bool,
     /// Avoid writing any fixed files back; instead, output a diff for each
-    /// changed file to stdout.
+    /// changed file to stdout. Implies `--fix-only`.
     #[arg(long, conflicts_with = "show_fixes")]
     pub diff: bool,
     /// Run in watch mode by re-running whenever files change.
diff --git a/docs/configuration.md b/docs/configuration.md
index dd82244fa7..f9ad5e7712 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -201,7 +201,7 @@ Options:
       --show-fixes
           Show an enumeration of all autofixed lint violations
       --diff
-          Avoid writing any fixed files back; instead, output a diff for each changed file to stdout
+          Avoid writing any fixed files back; instead, output a diff for each changed file to stdout. Implies `--fix-only`
   -w, --watch
           Run in watch mode by re-running whenever files change
       --fix-only