diff --git a/lms/djangoapps/grades/course_data.py b/lms/djangoapps/grades/course_data.py
index 56e462c247..4d2aad6774 100644
--- a/lms/djangoapps/grades/course_data.py
+++ b/lms/djangoapps/grades/course_data.py
@@ -106,7 +106,10 @@ class CourseData(object):
             return getattr(course_block, 'subtree_edited_on', None)
 
     def __str__(self):
-        return 'Course: course_key: {}'.format(self.course_key)
+        """
+        Return human-readable string representation.
+        """
+        return u'Course: course_key: {}'.format(self.course_key)
 
     def full_string(self):
         if self.effective_structure:
diff --git a/lms/djangoapps/grades/models.py b/lms/djangoapps/grades/models.py
index d415261e28..a887833ad3 100644
--- a/lms/djangoapps/grades/models.py
+++ b/lms/djangoapps/grades/models.py
@@ -20,6 +20,7 @@ import six
 from django.apps import apps
 from django.contrib.auth.models import User
 from django.db import models
+from django.utils.encoding import python_2_unicode_compatible
 from django.utils.timezone import now
 from lazy import lazy
 from model_utils.models import TimeStampedModel
@@ -79,7 +80,7 @@ class BlockRecordList(object):
         supported by adding a label indicated which algorithm was used, e.g.,
         "sha256$j0NDRmSPa5bfid2pAcUXaxCm2Dlh3TwayItZstwyeqQ=".
         """
-        return b64encode(sha1(self.json_value.encode('utf-8')).digest())
+        return b64encode(sha1(self.json_value.encode('utf-8')).digest()).decode('utf-8')
 
     @lazy
     def json_value(self):
@@ -128,6 +129,7 @@ class BlockRecordList(object):
         return cls(blocks, course_key)
 
 
+@python_2_unicode_compatible
 class VisibleBlocks(models.Model):
     """
     A django model used to track the state of a set of visible blocks under a
@@ -148,7 +150,7 @@ class VisibleBlocks(models.Model):
     class Meta(object):
         app_label = "grades"
 
-    def __unicode__(self):
+    def __str__(self):
         """
         String representation of this model.
         """
diff --git a/lms/djangoapps/grades/tests/test_models.py b/lms/djangoapps/grades/tests/test_models.py
index 7eda48c32a..a9e718755b 100644
--- a/lms/djangoapps/grades/tests/test_models.py
+++ b/lms/djangoapps/grades/tests/test_models.py
@@ -166,7 +166,7 @@ class VisibleBlocksTest(GradesModelTestCase):
             'version': BLOCK_RECORD_LIST_VERSION,
         }
         expected_json = json.dumps(expected_data, separators=(',', ':'), sort_keys=True)
-        expected_hash = b64encode(sha1(expected_json).digest())
+        expected_hash = b64encode(sha1(expected_json.encode('utf-8')).digest()).decode('utf-8')
         self.assertEqual(expected_data, json.loads(vblocks.blocks_json))
         self.assertEqual(expected_json, vblocks.blocks_json)
         self.assertEqual(expected_hash, vblocks.hashed)
diff --git a/lms/djangoapps/grades/transformer.py b/lms/djangoapps/grades/transformer.py
index 7470c8ac91..c1028c0590 100644
--- a/lms/djangoapps/grades/transformer.py
+++ b/lms/djangoapps/grades/transformer.py
@@ -93,7 +93,7 @@ class GradesTransformer(BlockStructureTransformer):
             separators=(',', ':'),  # Remove spaces from separators for more compact representation
             sort_keys=True,
         )
-        return b64encode(sha1(ordered_policy.encode('utf-8')).digest())
+        return b64encode(sha1(ordered_policy.encode('utf-8')).digest()).decode('utf-8')
 
     @classmethod
     def _collect_explicit_graded(cls, block_structure):