diff --git a/glymur/jp2box.py b/glymur/jp2box.py
index ab8a6e5..043a1be 100644
--- a/glymur/jp2box.py
+++ b/glymur/jp2box.py
@@ -145,8 +145,8 @@ class Jp2kBox(object):
         except KeyError:
             msg = 'Unrecognized box ({0}) encountered.'.format(box_id)
             warnings.warn(msg)
-            box = Jp2kBox(box_id, offset=start, length=num_bytes,
-                          longname='Unknown box')
+            box = UnknownBox(box_id, offset=start, length=num_bytes,
+                             longname='Unknown')
 
             if fptr.tell() != start + 8:
                 # If the file pointer has advanced, then the KeyError
@@ -2739,6 +2739,37 @@ class DataEntryURLBox(Jp2kBox):
         return box
 
 
+class UnknownBox(Jp2kBox):
+    """Container for unrecognized boxes.
+
+    Attributes
+    ----------
+    box_id : str
+        4-character identifier for the box.
+    length : int
+        length of the box in bytes.
+    offset : int
+        offset of the box from the start of the file.
+    longname : str
+        more verbose description of the box.
+    """
+    def __init__(self, box_id, length=0, offset=-1, longname=''):
+        Jp2kBox.__init__(self, box_id=box_id, longname=longname)
+        self.length = length
+        self.offset = offset
+
+    def __repr__(self):
+        msg = "glymur.jp2box.UnknownBox({0})".format(self.box_id)
+        return msg
+
+    def __str__(self):
+        if len(self.box) > 0:
+            msg = self._str_superbox()
+        else:
+            msg = Jp2kBox.__str__(self)
+        return msg
+
+
 class UUIDBox(Jp2kBox):
     """Container for UUID box information.
 
diff --git a/glymur/test/fixtures.py b/glymur/test/fixtures.py
index 6e0a76c..a7906c5 100644
--- a/glymur/test/fixtures.py
+++ b/glymur/test/fixtures.py
@@ -690,3 +690,11 @@ file7_rreq = r"""Reader Requirements Box (rreq) @ (44, 24)
         Feature 060:  0x60 e-sRGB enumerated colorspace
         Feature 043:  0x40 Deprecated - compositing layer uses restricted ICC profile
     Vendor Features:"""
+
+file1_xml = r"""XML Box (xml ) @ (36, 439)
+    <ns0:IMAGE_CREATION xmlns:ns0="http://www.jpeg.org/jpx/1.0/xml" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.jpeg.org/jpx/1.0/xml http://www.jpeg.org/metadata/15444-2.xsd">
+      <ns0:GENERAL_CREATION_INFO>
+        <ns0:CREATION_TIME>2001-11-01T13:45:00.000-06:00</ns0:CREATION_TIME>
+        <ns0:IMAGE_SOURCE>Professional 120 Image</ns0:IMAGE_SOURCE>
+      </ns0:GENERAL_CREATION_INFO>
+    </ns0:IMAGE_CREATION>"""
diff --git a/glymur/test/test_printing.py b/glymur/test/test_printing.py
index 5fe3322..132d1ec 100644
--- a/glymur/test/test_printing.py
+++ b/glymur/test/test_printing.py
@@ -39,6 +39,7 @@ from .fixtures import text_gbr_27, text_gbr_33, text_gbr_34
 class TestPrinting(unittest.TestCase):
     """Tests for verifying how printing works."""
     def setUp(self):
+        self.jpxfile = glymur.data.jpxfile()
         self.jp2file = glymur.data.nemo()
         self.j2kfile = glymur.data.goodstuff()
 
@@ -48,6 +49,31 @@ class TestPrinting(unittest.TestCase):
     def tearDown(self):
         pass
 
+    @unittest.skipIf(sys.hexversion < 0x03000000, "Needs unittest in 3.x.")
+    def test_unknown_superbox(self):
+        """Verify that we can handle an unknown superbox."""
+        with tempfile.NamedTemporaryFile(suffix='.jpx') as tfile:
+            with open(self.jpxfile, 'rb') as ifile:
+                tfile.write(ifile.read())
+            
+            # Add the header for an unknwon superbox.
+            write_buffer = struct.pack('>I4s', 20, 'grp '.encode())
+            tfile.write(write_buffer)
+            write_buffer = struct.pack('>I4sI', 12, 'free'.encode(), 0)
+            tfile.write(write_buffer)
+            tfile.flush()
+
+            with self.assertWarns(UserWarning):
+                jpx = Jp2k(tfile.name)
+            glymur.set_printoptions(short=True)
+            with patch('sys.stdout', new=StringIO()) as fake_out:
+                print(jpx.box[-1])
+                actual = fake_out.getvalue().strip()
+            lines = ['Unknown Box (grp ) @ (695609, 20)',
+                     '    Free Box (free) @ (695617, 12)']
+            expected = '\n'.join(lines)
+            self.assertEqual(actual, expected)
+
     def test_printoptions_bad_argument(self):
         """Verify error when bad parameter to set_printoptions"""
         with self.assertRaises(TypeError):
@@ -602,27 +628,7 @@ class TestPrinting(unittest.TestCase):
         with patch('sys.stdout', new=StringIO()) as fake_out:
             print(j.box[2])
             actual = fake_out.getvalue().strip()
-
-        lines = ['XML Box (xml ) @ (36, 439)',
-                 '    <ns0:IMAGE_CREATION '
-                 + 'xmlns:ns0="http://www.jpeg.org/jpx/1.0/xml" '
-                 + 'xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" '
-                 + 'xsi:schemaLocation="http://www.jpeg.org/jpx/1.0/xml '
-                 + 'http://www.jpeg.org/metadata/15444-2.xsd">',
-
-                 '      <ns0:GENERAL_CREATION_INFO>',
-                 '        <ns0:CREATION_TIME>'
-                 + '2001-11-01T13:45:00.000-06:00'
-                 + '</ns0:CREATION_TIME>',
-
-                 '        <ns0:IMAGE_SOURCE>'
-                 + 'Professional 120 Image'
-                 + '</ns0:IMAGE_SOURCE>',
-
-                 '      </ns0:GENERAL_CREATION_INFO>',
-                 '    </ns0:IMAGE_CREATION>']
-        expected = '\n'.join(lines)
-        self.assertEqual(actual, expected)
+        self.assertEqual(actual, fixtures.file1_xml)
 
     @unittest.skipIf(sys.hexversion < 0x03000000,
                      "Only trusting python3 for printing non-ascii chars")