diff --git a/Lib/_abcoll.py b/Lib/_abcoll.py
index ec3e2f8..6363de9 100644
--- a/Lib/_abcoll.py
+++ b/Lib/_abcoll.py
@@ -16,6 +16,7 @@
            "Mapping", "MutableMapping",
            "MappingView", "KeysView", "ItemsView", "ValuesView",
            "Sequence", "MutableSequence",
+           "ByteString",
            ]
 
 ### ONE-TRICK PONIES ###
@@ -489,8 +490,17 @@
 
 Sequence.register(tuple)
 Sequence.register(str)
-Sequence.register(bytes)
-Sequence.register(memoryview)
+
+
+class ByteString(Sequence):
+
+    """This unifies bytes and bytearray.
+
+    XXX Should add all their methods.
+    """
+
+ByteString.register(bytes)
+ByteString.register(bytearray)
 
 
 class MutableSequence(Sequence):
@@ -531,4 +541,4 @@
         self.extend(values)
 
 MutableSequence.register(list)
-MutableSequence.register(bytes)
+MutableSequence.register(bytearray)  # Multiply inheriting, see ByteString
diff --git a/Lib/test/test_collections.py b/Lib/test/test_collections.py
index 3ccc06c..62da9c5 100644
--- a/Lib/test/test_collections.py
+++ b/Lib/test/test_collections.py
@@ -8,6 +8,7 @@
 from collections import Set, MutableSet
 from collections import Mapping, MutableMapping
 from collections import Sequence, MutableSequence
+from collections import ByteString
 
 
 class TestNamedTuple(unittest.TestCase):
@@ -260,11 +261,21 @@
             self.failUnless(issubclass(sample, Sequence))
         self.failUnless(issubclass(str, Sequence))
 
+    def test_ByteString(self):
+        for sample in [bytes, bytearray]:
+            self.failUnless(isinstance(sample(), ByteString))
+            self.failUnless(issubclass(sample, ByteString))
+        for sample in [str, list, tuple]:
+            self.failIf(isinstance(sample(), ByteString))
+            self.failIf(issubclass(sample, ByteString))
+        self.failIf(isinstance(memoryview(b""), ByteString))
+        self.failIf(issubclass(memoryview, ByteString))
+
     def test_MutableSequence(self):
-        for sample in [tuple, str]:
+        for sample in [tuple, str, bytes]:
             self.failIf(isinstance(sample(), MutableSequence))
             self.failIf(issubclass(sample, MutableSequence))
-        for sample in [list, bytes]:
+        for sample in [list, bytearray]:
             self.failUnless(isinstance(sample(), MutableSequence))
             self.failUnless(issubclass(sample, MutableSequence))
         self.failIf(issubclass(str, MutableSequence))