diff --git a/rust/src/main.rs b/rust/src/main.rs
index 9293bc0..72ddf2c 100644
--- a/rust/src/main.rs
+++ b/rust/src/main.rs
@@ -121,15 +121,15 @@ fn iterator(input: &Path) -> impl Iterator<Item = PathBuf> {
         .into_iter()
         .filter_map(|e| e.ok())
         .filter(|e| e.file_type().is_file())
+        .filter(|e| !already_compressed(e.path()))
         .map(|e| e.path().to_owned())
-        .filter(|e| !already_compressed(e))
 }
 
 fn strip_input(path: &Path, input: &Path) -> PathBuf {
     path.strip_prefix(input).unwrap().to_owned()
 }
 
-fn already_compressed(path: &PathBuf) -> bool {
+fn already_compressed(path: &Path) -> bool {
     let p = path.to_string_lossy();
     p.ends_with(".br") || p.ends_with(".gz")
 }