diff --git a/.idea/dictionaries/herbert.xml b/.idea/dictionaries/herbert.xml
index c96d2ea..c942ae1 100644
--- a/.idea/dictionaries/herbert.xml
+++ b/.idea/dictionaries/herbert.xml
@@ -6,6 +6,7 @@
       <w>encrypter</w>
       <w>hmac</w>
       <w>kdbx</w>
+      <w>keepass</w>
     </words>
   </dictionary>
 </component>
\ No newline at end of file
diff --git a/lib/src/kdbx_header.dart b/lib/src/kdbx_header.dart
index 2cb7365..06454d0 100644
--- a/lib/src/kdbx_header.dart
+++ b/lib/src/kdbx_header.dart
@@ -227,18 +227,26 @@ class KdbxHeader {
     _validateInner();
     for (final field in InnerHeaderFields.values
         .where((f) => f != InnerHeaderFields.EndOfHeader)) {
-      _writeInnerField(writer, field);
+      _writeInnerFieldIfExist(writer, field);
+    }
+    // write attachments
+    for (final binary in innerHeader.binaries) {
+      _writeInnerField(writer, binary);
     }
-    // TODO write attachments
     _setInnerHeaderField(InnerHeaderFields.EndOfHeader, Uint8List(0));
-    _writeInnerField(writer, InnerHeaderFields.EndOfHeader);
+    _writeInnerFieldIfExist(writer, InnerHeaderFields.EndOfHeader);
   }
 
-  void _writeInnerField(WriterHelper writer, InnerHeaderFields field) {
+  void _writeInnerFieldIfExist(WriterHelper writer, InnerHeaderFields field) {
     final value = innerHeader.fields[field];
     if (value == null) {
       return;
     }
+    _writeInnerField(writer, value);
+  }
+
+  void _writeInnerField(WriterHelper writer, InnerHeaderField value) {
+    final field = value.field;
     _logger.finer(
         'Writing header $field (${field.index}) (${value.bytes.lengthInBytes})');
     writer.writeUint8(field.index);
@@ -438,6 +446,11 @@ class KdbxCorruptedFileException implements KdbxException {
   KdbxCorruptedFileException([this.message]);
 
   final String message;
+
+  @override
+  String toString() {
+    return 'KdbxCorruptedFileException{message: $message}';
+  }
 }
 
 class KdbxUnsupportedException implements KdbxException {
diff --git a/test/internal/test_utils.dart b/test/internal/test_utils.dart
index 873d35b..8d788e4 100644
--- a/test/internal/test_utils.dart
+++ b/test/internal/test_utils.dart
@@ -1,6 +1,7 @@
 //typedef HashStuff = Pointer<Utf8> Function(Pointer<Utf8> str);
 import 'dart:ffi';
 import 'dart:io';
+import 'dart:typed_data';
 
 import 'package:ffi/ffi.dart';
 import 'package:kdbx/kdbx.dart';
@@ -55,4 +56,12 @@ class TestUtil {
         data, Credentials(ProtectedValue.fromString(password)));
     return file;
   }
+
+  static Future<KdbxFile> readKdbxFileBytes(Uint8List data,
+      {String password = 'asdf'}) async {
+    final kdbxFormat = KdbxFormat(Argon2Test());
+    final file = await kdbxFormat.read(
+        data, Credentials(ProtectedValue.fromString(password)));
+    return file;
+  }
 }
diff --git a/test/kdbx_binaries_test.dart b/test/kdbx_binaries_test.dart
index 1a92ee4..b05a8ab 100644
--- a/test/kdbx_binaries_test.dart
+++ b/test/kdbx_binaries_test.dart
@@ -8,14 +8,20 @@ import 'package:test/test.dart';
 
 import 'internal/test_utils.dart';
 
+void expectBinary(KdbxEntry entry, String key, dynamic matcher) {
+  final binaries = entry.binaryEntries;
+  expect(binaries, hasLength(1));
+  final binary = binaries.first;
+  expect(binary.key.key, key);
+  expect(binary.value.value, matcher);
+}
+
 void main() {
   Logger.root.level = Level.ALL;
   PrintAppender().attachToLogger(Logger.root);
 
   group('kdbx3 attachment', () {
-    test('read binary', () async {
-      final file = await TestUtil.readKdbxFile('test/keepass2binaries.kdbx');
-      final entry = file.body.rootGroup.entries.first;
+    void expectKeepass2binariesContents(KdbxEntry entry) {
       final binaries = entry.binaryEntries;
       expect(binaries, hasLength(3));
       for (final binary in binaries) {
@@ -33,19 +39,26 @@ void main() {
             fail('invalid key. ${binary.key}');
         }
       }
+    }
+
+    test('read binary', () async {
+      final file = await TestUtil.readKdbxFile('test/keepass2binaries.kdbx');
+      final entry = file.body.rootGroup.entries.first;
+      expectKeepass2binariesContents(entry);
+    });
+    test('read write read', () async {
+      final fileRead =
+          await TestUtil.readKdbxFile('test/keepass2binaries.kdbx');
+      final saved = await fileRead.save();
+      final file = await TestUtil.readKdbxFileBytes(saved);
+      final entry = file.body.rootGroup.entries.first;
+      expectKeepass2binariesContents(entry);
     });
   });
   group('kdbx4 attachment', () {
     test('read binary', () async {
       final file =
           await TestUtil.readKdbxFile('test/keepass2kdbx4binaries.kdbx');
-      void expectBinary(KdbxEntry entry, String key, dynamic matcher) {
-        final binaries = entry.binaryEntries;
-        expect(binaries, hasLength(1));
-        final binary = binaries.first;
-        expect(binary.key.key, key);
-        expect(binary.value.value, matcher);
-      }
 
       expect(file.body.rootGroup.entries, hasLength(2));
       expectBinary(file.body.rootGroup.entries.first, 'example2.txt',
@@ -54,6 +67,17 @@ void main() {
           hasLength(7092));
     });
   });
+  test('read, write, read', () async {
+    final fileRead =
+        await TestUtil.readKdbxFile('test/keepass2kdbx4binaries.kdbx');
+    final saved = await fileRead.save();
+    final file = await TestUtil.readKdbxFileBytes(saved);
+    expect(file.body.rootGroup.entries, hasLength(2));
+    expectBinary(file.body.rootGroup.entries.first, 'example2.txt',
+        IsUtf8String('content2 example\n\n'));
+    expectBinary(
+        file.body.rootGroup.entries.last, 'keepasslogo.jpeg', hasLength(7092));
+  });
 }
 
 class IsUtf8String extends CustomMatcher {