diff --git a/django/core/serializers/json.py b/django/core/serializers/json.py
index 1b9a61750d..937d839239 100644
--- a/django/core/serializers/json.py
+++ b/django/core/serializers/json.py
@@ -8,7 +8,6 @@ from __future__ import absolute_import
 import datetime
 import decimal
 import json
-from io import BytesIO
 
 from django.core.serializers.base import DeserializationError
 from django.core.serializers.python import Serializer as PythonSerializer
@@ -63,13 +62,13 @@ def Deserializer(stream_or_string, **options):
     Deserialize a stream or string of JSON data.
     """
     if isinstance(stream_or_string, bytes):
-        stream = BytesIO(stream_or_string)
-    elif isinstance(stream_or_string, unicode):
-        stream = BytesIO(smart_str(stream_or_string))
-    else:
-        stream = stream_or_string
+        stream_or_string = stream_or_string.decode('utf-8')
     try:
-        for obj in PythonDeserializer(json.load(stream), **options):
+        if isinstance(stream_or_string, basestring):
+            objects = json.loads(stream_or_string)
+        else:
+            objects = json.load(stream_or_string)
+        for obj in PythonDeserializer(objects, **options):
             yield obj
     except GeneratorExit:
         raise
diff --git a/django/core/serializers/pyyaml.py b/django/core/serializers/pyyaml.py
index e490b8607d..b639ad2dae 100644
--- a/django/core/serializers/pyyaml.py
+++ b/django/core/serializers/pyyaml.py
@@ -6,7 +6,7 @@ Requires PyYaml (http://pyyaml.org/), but that's checked for in __init__.
 
 import decimal
 import yaml
-from io import BytesIO
+from io import StringIO
 
 from django.db import models
 from django.core.serializers.base import DeserializationError
@@ -51,9 +51,9 @@ def Deserializer(stream_or_string, **options):
     Deserialize a stream or string of YAML data.
     """
     if isinstance(stream_or_string, bytes):
-        stream = BytesIO(stream_or_string)
-    if isinstance(stream_or_string, unicode):
-        stream = BytesIO(smart_str(stream_or_string))
+        stream_or_string = stream_or_string.decode('utf-8')
+    if isinstance(stream_or_string, basestring):
+        stream = StringIO(stream_or_string)
     else:
         stream = stream_or_string
     try: