diff --git a/flask_heroku.py b/flask_heroku.py
index 392ea2f..3566fd4 100644
--- a/flask_heroku.py
+++ b/flask_heroku.py
@@ -16,6 +16,9 @@ class Heroku(object):
             self.init_app(app)
 
     def init_app(self, app):
+        # app.secret_key
+        app.config.setdefault('SECRET_KEY', environ.get('SECRET_KEY'))
+
         # SQL-Alchemy
         app.config.setdefault('SQLALCHEMY_DATABASE_URI', environ.get('DATABASE_URL'))