diff --git a/picard/formats/id3.py b/picard/formats/id3.py
index 8c2d8f097..942064334 100644
--- a/picard/formats/id3.py
+++ b/picard/formats/id3.py
@@ -358,9 +358,9 @@ class ID3File(File):
                     tmcl.people.append([role, value])
             elif name.startswith('comment:'):
                 desc = name.split(':', 1)[1]
-                if desc.lower()[:4] == "itun":
+                if desc.lower()[:4] == 'itun':
                     tags.delall('COMM:' + desc)
-                    tags.add(id3.COMM(encoding=0, desc=desc, lang='eng', text=[v + b'\x00' for v in values]))
+                    tags.add(id3.COMM(encoding=0, desc=desc, lang='eng', text=[v + '\x00' for v in values]))
                 else:
                     tags.add(id3.COMM(encoding=encoding, desc=desc, lang='eng', text=values))
             elif name.startswith('lyrics:') or name == 'lyrics':
diff --git a/test/test_formats.py b/test/test_formats.py
index d9ca2201d..d3a4511f1 100644
--- a/test/test_formats.py
+++ b/test/test_formats.py
@@ -436,6 +436,15 @@ class CommonTests:
             self.assertIn(metadata['work'], loaded_metadata['work'])
             self.assertEqual(loaded_metadata['grouping'], '')
 
+        @skipUnlessTestfile
+        def test_save_itunnorm_tag(self):
+            config.setting['clear_existing_tags'] = True
+            iTunNORM = '00001E86 00001E86 0000A2A3 0000A2A3 000006A6 000006A6 000078FA 000078FA 00000211 00000211'
+            metadata = Metadata()
+            metadata['comment:iTunNORM'] = iTunNORM
+            new_metadata = save_and_load_metadata(self.filename, metadata)
+            self.assertEqual(new_metadata['comment:iTunNORM'], iTunNORM)
+
 
 class FLACTest(CommonTests.FormatsTest):
     testfile = 'test.flac'