diff --git a/zarr/storage.py b/zarr/storage.py
index d71ee3a18a..656b05acf8 100644
--- a/zarr/storage.py
+++ b/zarr/storage.py
@@ -2147,7 +2147,15 @@ def __getitem__(self, key):
         if doc is None:
             raise KeyError(key)
         else:
-            return binary_type(doc[self._value])
+            value = doc[self._value]
+
+            # Coerce `bson.Binary` to `bytes` type on Python 2.
+            # PyMongo handles this conversion for us on Python 3.
+            # ref: http://api.mongodb.com/python/current/python3.html#id3
+            if PY2:  # pragma: py3 no cover
+                value = binary_type(value)
+
+            return value
 
     def __setitem__(self, key, value):
         value = ensure_bytes(value)