diff --git a/setup.py b/setup.py
index f141c62..eb7a197 100755
--- a/setup.py
+++ b/setup.py
@@ -120,9 +120,10 @@ setup(name='biomon',
             ],
         },
         install_requires=[
-            'django >= 1.8.2',
-            'matplotlib>=1.4.3',
-            'whisper>=0.9.13',
+            'django=1.8.2',
+            'matplotlib=1.4.3',
+            'whisper=0.9.13',
+            'simplejson=3.8.0',
         ],
         cmdclass={
             'build': build,