diff --git a/src/pax.rs b/src/pax.rs
index d1494282..6c60f634 100644
--- a/src/pax.rs
+++ b/src/pax.rs
@@ -147,7 +147,7 @@ impl<'entry> PaxExtension<'entry> {
     }
 }
 
-/// Extension trait for `Builder` to append PAX extended headers.
+/// Implement `Builder` to append PAX extended headers.
 impl<T: Write> crate::Builder<T> {
     /// Append PAX extended headers to the archive.
     ///
@@ -156,7 +156,7 @@ impl<T: Write> crate::Builder<T> {
     /// Returns io::Error if an error occurs, else it returns ()
     pub fn append_pax_extensions<'key, 'value>(
         &mut self,
-        headers: impl IntoIterator<Item = (&'key str, &'value [u8])>,
+        headers: impl IntoIterator<Item = (&'key [u8], &'value [u8])>,
     ) -> Result<(), io::Error> {
         // Store the headers formatted before write
         let mut data: Vec<u8> = Vec::new();
@@ -172,7 +172,9 @@ impl<T: Write> crate::Builder<T> {
                 max_len *= 10;
             }
             let len = rest_len + len_len;
-            write!(&mut data, "{} {}=", len, key)?;
+            write!(&mut data, "{} ", len)?;
+            data.extend_from_slice(key);
+            data.push(b'=');
             data.extend_from_slice(value);
             data.push(b'\n');
         }
diff --git a/tests/all.rs b/tests/all.rs
index 0e1c2613..42a2597c 100644
--- a/tests/all.rs
+++ b/tests/all.rs
@@ -933,8 +933,11 @@ fn pax_simple_write() {
     let mut ar: Builder<BufWriter<File>> = Builder::new(BufWriter::new(file));
 
     let pax_extensions = [
-        ("arbitrary_pax_key", b"arbitrary_pax_value".as_slice()),
-        ("SCHILY.xattr.security.selinux", b"foo_t"),
+        (
+            b"arbitrary_pax_key".as_slice(),
+            b"arbitrary_pax_value".as_slice(),
+        ),
+        (b"SCHILY.xattr.security.selinux".as_slice(), b"foo_t"),
     ];
 
     t!(ar.append_pax_extensions(pax_extensions));
@@ -953,7 +956,10 @@ fn pax_simple_write() {
     assert_eq!(pax_arbitrary.key(), Ok("arbitrary_pax_key"));
     assert_eq!(pax_arbitrary.value(), Ok("arbitrary_pax_value"));
     let xattr = t!(pax_headers.next().unwrap());
-    assert_eq!(xattr.key().unwrap(), pax_extensions[1].0);
+    assert_eq!(
+        xattr.key().unwrap(),
+        std::str::from_utf8(pax_extensions[1].0).unwrap()
+    );
     assert_eq!(xattr.value_bytes(), pax_extensions[1].1);
 
     assert!(entries.next().is_none());