Try import django.utils.simplejson, except import json

compressor/cache.py

@@ -1,4 +1,3 @@
-import json
 import hashlib
 import os
 import socket
@@ -10,6 +9,11 @@ from django.utils.encoding import force_text, smart_bytes
 from django.utils.functional import SimpleLazyObject
 from django.utils.importlib import import_module
 
+try:
+    import django.utils.simplejson as json
+except ImportError:
+    import json
+
 from compressor.conf import settings
 from compressor.storage import default_storage
 from compressor.utils import get_mod_func