diff --git a/front/Cargo.toml b/front/Cargo.toml
index d01670b..db31328 100644
--- a/front/Cargo.toml
+++ b/front/Cargo.toml
@@ -16,4 +16,7 @@ name = "alejandra_front"
 repository = "https://github.com/kamadorueda/alejandra"
 version = "0.3.1"
 
+[profile.release]
+lto = true
+
 [workspace]
diff --git a/src/alejandra_cli/src/cli.rs b/src/alejandra_cli/src/cli.rs
index 8e60c4d..73aa6bb 100644
--- a/src/alejandra_cli/src/cli.rs
+++ b/src/alejandra_cli/src/cli.rs
@@ -3,10 +3,18 @@ pub fn parse(args: Vec<String>) -> clap::ArgMatches {
         .about("The Uncompromising Nix Code Formatter.")
         .version(alejandra_engine::version::VERSION)
         .arg(
-            clap::Arg::new("paths")
+            clap::Arg::new("include")
                 .help("Files or directories, or none to format stdin.")
                 .multiple_values(true),
         )
+        .arg(
+            clap::Arg::new("exclude")
+                .short('e')
+                .help("Files or directories to exclude from formatting.")
+                .long("exclude")
+                .multiple_occurrences(true)
+                .takes_value(true),
+        )
         .term_width(80)
         .after_help(indoc::indoc!(
             // Let's just use the same sorting as on GitHub
@@ -240,12 +248,12 @@ pub fn tui(
                         .bg(tui::style::Color::Black)
                         .add_modifier(tui::style::Modifier::ITALIC),
                 )
-                .percent(
-                    (100 * (paths_changed
-                        + paths_unchanged
-                        + paths_with_errors)
-                        / paths_to_format) as u16,
-                )
+                .percent(if paths_to_format == 0 {
+                    100
+                } else {
+                    100 * (paths_changed + paths_unchanged + paths_with_errors)
+                        / paths_to_format
+                } as u16)
                 .style(
                     tui::style::Style::default()
                         .bg(tui::style::Color::Black)
diff --git a/src/alejandra_cli/src/find.rs b/src/alejandra_cli/src/find.rs
index 204d99b..77e8f12 100644
--- a/src/alejandra_cli/src/find.rs
+++ b/src/alejandra_cli/src/find.rs
@@ -1,11 +1,17 @@
-pub fn nix_files(paths: Vec<&str>) -> Vec<String> {
+pub fn nix_files(include: Vec<&str>, exclude: Vec<&str>) -> Vec<String> {
+    let include: std::collections::HashSet<String> =
+        include.iter().flat_map(nix_files_in_path).collect();
+    let exclude: std::collections::HashSet<String> =
+        exclude.iter().flat_map(nix_files_in_path).collect();
+
     let mut paths: Vec<String> =
-        paths.iter().flat_map(nix_files_in_path).collect();
+        include.difference(&exclude).map(|path| path.clone()).collect();
+
     paths.sort();
     paths
 }
 
-fn nix_files_in_path(path: &&str) -> Vec<String> {
+fn nix_files_in_path(path: &&str) -> std::collections::HashSet<String> {
     walkdir::WalkDir::new(path)
         .into_iter()
         .filter_entry(is_nix_file_or_dir)
diff --git a/src/alejandra_cli/src/main.rs b/src/alejandra_cli/src/main.rs
index 97edebe..5aaf90a 100644
--- a/src/alejandra_cli/src/main.rs
+++ b/src/alejandra_cli/src/main.rs
@@ -3,10 +3,16 @@ fn main() -> std::io::Result<()> {
 
     let config = alejandra_engine::config::Config::default();
 
-    match matches.values_of("paths") {
-        Some(paths) => {
+    match matches.values_of("include") {
+        Some(include) => {
+            let include = include.collect();
+            let exclude = match matches.values_of("exclude") {
+                Some(exclude) => exclude.collect(),
+                None => vec![],
+            };
+
             let paths: Vec<String> =
-                alejandra_cli::find::nix_files(paths.collect());
+                alejandra_cli::find::nix_files(include, exclude);
 
             if atty::is(atty::Stream::Stderr)
                 && atty::is(atty::Stream::Stdin)