diff --git a/src/app.rs b/src/app.rs
index 2c19683..ebb4612 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -248,53 +248,87 @@ fn build(mode: &Option<String>, force_recompile: bool) -> std::io::Result<()> {
 
     let start = std::time::Instant::now();
 
-    std::fs::create_dir_all(format!("target/{}", build_config.name))?;
+    let obj_dir = format!("target/{}/obj", build_config.name);
 
-    let hash = hash_src_tree()?;
+    std::fs::create_dir_all(&obj_dir)?;
 
-    let old_compute_path = PathBuf::from(format!("target/{}/.build_hash", build_config.name));
+    let compiler = conf.compiler.as_deref().unwrap_or("gcc");
 
-    if old_compute_path.exists() && !force_recompile {
-        let text = std::fs::read_to_string(old_compute_path)?;
+    let source_files: Vec<PathBuf> = glob("src/*.c")
+        .map_err(|e| std::io::Error::new(std::io::ErrorKind::NotFound, format!("{e}")))?
+        .filter_map(|e| e.ok())
+        .collect();
 
-        if hash.trim() == text.trim() {
-            println!(
-                "   {} (code not changed, recompile not made)",
-                "Finished".green().bold()
-            );
-            return Ok(());
+    let mut any_changed = false;
+
+    for src in &source_files {
+        let stem = src.file_stem().unwrap().to_string_lossy();
+        let obj_path = format!("{}/{}.o", obj_dir, stem);
+        let hash_path = format!("{}/{}.c.hash", obj_dir, stem);
+
+        let hash = hash_file(src)?;
+
+        let needs_compile = force_recompile
+            || match std::fs::read_to_string(&hash_path) {
+                Ok(old) => old.trim() != hash.trim(),
+                Err(_) => true,
+            };
+
+        if needs_compile {
+            println!(" {} {}", "Compiling".green().bold(), src.display());
+
+            let status = Command::new(compiler)
+                .args(&build_config.args)
+                .arg("-c")
+                .arg(src)
+                .arg("-o")
+                .arg(&obj_path)
+                .status()?;
+
+            if !status.success() {
+                return Err(std::io::Error::new(
+                    std::io::ErrorKind::Other,
+                    format!("failed to compile {}", src.display()),
+                ));
+            }
+
+            std::fs::write(&hash_path, &hash)?;
+            any_changed = true;
         }
     }
 
-    let mut command = Command::new(conf.compiler.as_deref().unwrap_or("gcc"));
+    let binary = format!("target/{}/{}", build_config.name, conf.name);
+    let binary_exists = PathBuf::from(&binary).exists();
 
-    for arg in &build_config.args {
-        command.arg(arg);
+    if !any_changed && binary_exists {
+        println!(
+            "   {} (code not changed, recompile not made)",
+            "Finished".green().bold()
+        );
+        return Ok(());
     }
 
-    for entry in glob("src/*.c")
-        .map_err(|e| std::io::Error::new(std::io::ErrorKind::NotFound, format!("{e}").as_str()))?
-    {
-        if let Ok(path) = entry {
-            command.arg(path.to_string_lossy().to_string());
-        }
-    }
+    let obj_files: Vec<String> = source_files
+        .iter()
+        .map(|src| {
+            let stem = src.file_stem().unwrap().to_string_lossy();
+            format!("{}/{}.o", obj_dir, stem)
+        })
+        .collect();
 
-    command
+    let status = Command::new(compiler)
+        .args(&obj_files)
         .arg("-o")
-        .arg(format!("target/{}/{}", build_config.name, conf.name));
-
-    let status = command.status()?;
+        .arg(&binary)
+        .status()?;
 
     if !status.success() {
         return Err(std::io::Error::new(
             std::io::ErrorKind::Other,
-            format!("compiler exited with status {status}"),
+            "linking failed",
         ));
     }
 
-    std::fs::write(format!("target/{}/.build_hash", build_config.name), hash)?;
-
     let stop = start.elapsed();
 
     println!(
@@ -308,16 +342,9 @@ fn build(mode: &Option<String>, force_recompile: bool) -> std::io::Result<()> {
     Ok(())
 }
 
-fn hash_src_tree() -> std::io::Result<String> {
-    let mut hashes = String::new();
-    for entry in glob("src/**/*").expect("a valid glob pattern") {
-        if let Ok(file) = entry {
-            let text = std::fs::read_to_string(file)?;
-            let hash = sha256::digest(text);
-            hashes.push_str(hash.as_str());
-        }
-    }
-    Ok(sha256::digest(hashes))
+fn hash_file(path: &Path) -> std::io::Result<String> {
+    let contents = std::fs::read_to_string(path)?;
+    Ok(sha256::digest(contents))
 }
 
 fn run(mode: &Option<String>, args: Option<Vec<String>>) -> std::io::Result<()> {