diff --git a/glymur/jp2k.py b/glymur/jp2k.py
index dbdafd7..733a888 100644
--- a/glymur/jp2k.py
+++ b/glymur/jp2k.py
@@ -65,6 +65,13 @@ _INFO_CALLBACK = _CMPFUNC(_default_info_handler)
 _WARNING_CALLBACK = _CMPFUNC(_default_warning_handler)
 
 
+class LibraryNotFoundError(IOError):
+    """Raised if functionality is requested without the necessary library.
+    """
+    def __init__(self, msg):
+        IOError.__init__(self, msg)
+
+
 class Jp2k(Jp2kBox):
     """JPEG 2000 file.
 
@@ -225,10 +232,16 @@ class Jp2k(Jp2kBox):
         >>> tfile = NamedTemporaryFile(suffix='.jp2', delete=False)
         >>> j = Jp2k(tfile.name, mode='wb')
         >>> j.write(data.astype(np.uint8))
+
+        Raises
+        ------
+        glymur.LibraryNotFoundError
+            If glymur is unable to load the openjp2 library.
         """
         if _opj2.OPENJP2 is None:
-            raise IOError("You must have the development version of OpenJP2 "
-                          "installed before using this functionality.")
+            raise LibraryNotFoundError("You must have the development version "
+                                       "of OpenJP2 installed before using "
+                                       "this functionality.")
 
         cparams = _opj2.set_default_encoder_parameters()
 
@@ -577,7 +590,7 @@ class Jp2k(Jp2kBox):
         rlevel : int, optional
             Factor by which to rlevel output resolution.  Use -1 to get the
             lowest resolution thumbnail.  This is the only keyword option
-            available to use when only OpenJPEG version 1.5.1 is present.
+            available to use when only the OpenJPEG version 1.5.1 is present.
         layer : int, optional
             Number of quality layer to decode.
         area : tuple, optional
@@ -595,6 +608,9 @@ class Jp2k(Jp2kBox):
 
         Raises
         ------
+        glymur.LibraryNotFoundError
+            If glymur is unable to load either the openjpeg or openjp2
+            libraries.
         IOError
             If the image has differing subsample factors.
 
@@ -618,9 +634,10 @@ class Jp2k(Jp2kBox):
         elif _opj.OPENJPEG is not None:
             img = self._read_openjpeg(**kwargs)
         else:
-            raise IOError("You must have either a recent version of OpenJPEG "
-                          "or the development version of OpenJP2 installed "
-                          "before using this functionality.")
+            raise LibraryNotFoundError("You must have either a recent version "
+                                       "of OpenJPEG or the development "
+                                       "version of OpenJP2 installed before "
+                                       "using this functionality.")
         return img
 
     def _read_openjpeg(self, rlevel=0, verbose=False):
@@ -964,12 +981,13 @@ class Jp2k(Jp2kBox):
 
         Raises
         ------
-        NotImplementedError
-            If the openjp2 library is not available.
+        glymur.LibraryNotFoundError
+            If glymur is unable to load the openjp2 library.
         """
         if _opj2.OPENJP2 is None:
-            raise IOError("You must have the development version of OpenJP2 "
-                          "installed before using this functionality.")
+            raise LibraryNotFoundError("You must have the development version "
+                                       "of OpenJP2 installed before using "
+                                       "this functionality.")
 
         lst = self._read_common(rlevel=rlevel,
                                 layer=layer,
diff --git a/glymur/test/test_jp2k.py b/glymur/test/test_jp2k.py
index 4467b5c..43eaade 100644
--- a/glymur/test/test_jp2k.py
+++ b/glymur/test/test_jp2k.py
@@ -61,7 +61,7 @@ class TestConfig(unittest.TestCase):
         """
         with patch('glymur.lib.openjp2.OPENJP2', new=None):
             with  patch('glymur.lib.openjpeg.OPENJPEG', new=None):
-                with self.assertRaises((IOError, OSError)):
+                with self.assertRaises(glymur.jp2k.LibraryNotFoundError):
                     d = glymur.Jp2k(self.jp2file).read()
 
     def test_read_bands_without_library_backing_us_up(self):
@@ -69,7 +69,7 @@ class TestConfig(unittest.TestCase):
         """
         with patch('glymur.lib.openjp2.OPENJP2', new=None):
             with  patch('glymur.lib.openjpeg.OPENJPEG', new=None):
-                with self.assertRaises((IOError, OSError)):
+                with self.assertRaises(glymur.jp2k.LibraryNotFoundError):
                     d = glymur.Jp2k(self.jp2file).read_bands()
 
     @unittest.skipIf(os.name == "nt", "NamedTemporaryFile issue on windows")
@@ -79,7 +79,7 @@ class TestConfig(unittest.TestCase):
         data = glymur.Jp2k(self.j2kfile).read()
         with patch('glymur.lib.openjp2.OPENJP2', new=None):
             with  patch('glymur.lib.openjpeg.OPENJPEG', new=None):
-                with self.assertRaises((IOError, OSError)):
+                with self.assertRaises(glymur.jp2k.LibraryNotFoundError):
                     with tempfile.NamedTemporaryFile(suffix='.jp2') as tfile:
                         ofile = Jp2k(tfile.name, 'wb')
                         ofile.write(data)