diff --git a/glymur/jp2box.py b/glymur/jp2box.py
index 2b012b8..99a1dee 100644
--- a/glymur/jp2box.py
+++ b/glymur/jp2box.py
@@ -1538,7 +1538,7 @@ class XMLBox(Jp2kBox):
         XML section.
     """
     def __init__(self, **kwargs):
-        Jp2kBox.__init__(self, id='', longname='XML')
+        Jp2kBox.__init__(self, id='xml ', longname='XML')
         self.__dict__.update(**kwargs)
 
     def __str__(self):
@@ -1550,6 +1550,14 @@ class XMLBox(Jp2kBox):
             msg += '\n    {0}'.format(xml)
         return msg
 
+    def _write(self, f):
+        """Write an XML box to file.
+        """
+        buffer = ET.tostring(self.xml, encoding='utf-8')
+        f.write(struct.pack('>I', len(buffer) + 8))
+        f.write(self.id.encode())
+        f.write(buffer)
+
     @staticmethod
     def _parse(f, id, offset, length):
         """Parse XML box.
diff --git a/glymur/test/test_jp2box.py b/glymur/test/test_jp2box.py
index 8c0730b..2562339 100644
--- a/glymur/test/test_jp2box.py
+++ b/glymur/test/test_jp2box.py
@@ -1,5 +1,6 @@
 import doctest
 import tempfile
+import xml.etree.cElementTree as ET
 import unittest
 
 import numpy as np
@@ -47,6 +48,13 @@ class TestJp2Boxes(unittest.TestCase):
     def tearDown(self):
         pass
 
+    def test_default_XML(self):
+        # Should be able to instantiate an XMLBox
+        xml = ET.fromstring('<?xml version="1.0"?><data>0</data>')
+        b = glymur.jp2box.XMLBox(xml=xml)
+        self.assertEqual(ET.tostring(b.xml),
+                         b'<data>0</data>')
+
     def test_default_JPEG2000SignatureBox(self):
         # Should be able to instantiate a JPEG2000SignatureBox
         b = glymur.jp2box.JPEG2000SignatureBox()
@@ -217,10 +225,6 @@ class TestJp2Boxes(unittest.TestCase):
             with self.assertRaises(NotImplementedError):
                 j2k.wrap(tfile.name, boxes=boxes)
 
-    def test_default_xml(self):
-        # Should be able to write an xml box.
-        self.assertTrue(False)
-
     def test_default_component_definition(self):
         # Should be able to specify a component definition box in order to,
         # say, create an image with an alpha layer.
@@ -306,6 +310,49 @@ class TestJp2Boxes(unittest.TestCase):
             with self.assertRaises(IOError):
                 j2k.wrap(tfile.name, boxes=boxes)
 
+    def test_missing_colr_box(self):
+        j2k = Jp2k(self.raw_codestream)
+        c = j2k.get_codestream()
+        height = c.segment[1].Ysiz
+        width = c.segment[1].Xsiz
+        num_components = len(c.segment[1].XRsiz)
+
+        jP = JPEG2000SignatureBox()
+        ftyp = FileTypeBox()
+        jp2h = JP2HeaderBox()
+        jp2c = ContiguousCodestreamBox()
+        ihdr = ImageHeaderBox(height=height, width=width,
+                              num_components=num_components)
+        jp2h.box = [ihdr]
+        boxes = [jP, ftyp, jp2h, jp2c]
+        with tempfile.NamedTemporaryFile(suffix=".jp2") as tfile:
+            with self.assertRaises(IOError):
+                j2k.wrap(tfile.name, boxes=boxes)
+
+    def test_basic_xml(self):
+        j2k = Jp2k(self.raw_codestream)
+        c = j2k.get_codestream()
+        height = c.segment[1].Ysiz
+        width = c.segment[1].Xsiz
+        num_components = len(c.segment[1].XRsiz)
+
+        jP = JPEG2000SignatureBox()
+        ftyp = FileTypeBox()
+        jp2h = JP2HeaderBox()
+        jp2c = ContiguousCodestreamBox()
+        ihdr = ImageHeaderBox(height=height, width=width,
+                              num_components=num_components)
+        colr = ColourSpecificationBox(colorspace=glymur.core.SRGB)
+        jp2h.box = [ihdr, colr]
+
+        the_xml = ET.fromstring('<?xml version="1.0"?><data>0</data>')
+        xml = glymur.jp2box.XMLBox(xml=the_xml)
+        boxes = [jP, ftyp, jp2h, xml, jp2c]
+        with tempfile.NamedTemporaryFile(suffix=".jp2") as tfile:
+            j2k.wrap(tfile.name, boxes=boxes)
+            jp2 = Jp2k(tfile.name)
+            self.assertEqual(jp2.box[3].id, 'xml ')
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/glymur/test/test_jp2k.py b/glymur/test/test_jp2k.py
index b15ca35..479c1d7 100644
--- a/glymur/test/test_jp2k.py
+++ b/glymur/test/test_jp2k.py
@@ -15,7 +15,6 @@ if sys.hexversion <= 0x03030000:
 else:
     from unittest.mock import patch
 import warnings
-from xml.etree import cElementTree as ET
 
 import numpy as np
 import pkg_resources