diff --git a/django/db/backends/oracle/base.py b/django/db/backends/oracle/base.py
index 11ab5744ce..9b07b9dcb7 100644
--- a/django/db/backends/oracle/base.py
+++ b/django/db/backends/oracle/base.py
@@ -446,7 +446,7 @@ WHEN (new.%(col_name)s IS NULL)
         bounds = super(DatabaseOperations, self).year_lookup_bounds_for_datetime_field(value)
         if settings.USE_TZ:
             bounds = [b.astimezone(timezone.utc).replace(tzinfo=None) for b in bounds]
-        return [b.isoformat(b' ') for b in bounds]
+        return [b.isoformat(str(' ')) for b in bounds]
 
     def combine_expression(self, connector, sub_expressions):
         "Oracle requires special cases for %% and & operators in query expressions"
diff --git a/docs/releases/1.6.5.txt b/docs/releases/1.6.5.txt
index 9c612f7454..9abe6702cc 100644
--- a/docs/releases/1.6.5.txt
+++ b/docs/releases/1.6.5.txt
@@ -9,4 +9,5 @@ Django 1.6.5 fixes several bugs in 1.6.4.
 Bugfixes
 ========
 
-* ...
+* Made the ``year_lookup_bounds_for_datetime_field`` Oracle backend method
+  Python 3 compatible (`#22551 <http://code.djangoproject.com/ticket/22551>`_).