diff --git a/Large-app-how-to.md b/Large-app-how-to.md
index 4c93a86..36fa2ef 100644
--- a/Large-app-how-to.md
+++ b/Large-app-how-to.md
@@ -114,7 +114,7 @@ We'll create 4 modules, an user module (manage user's registration, login, lost
 ```
 
 * `_basedir` is a trick for you to get the folder where the script runs
-* `DEBUG` indicates that it is a dev environment, you'll get the very helpful error page from flask when an error occur.
+* `DEBUG` indicates that it is a dev environment, you'll get the very helpful error page from flask when an error occured.
 * `SECRET_KEY` will be use to sign the cookies. Change it and all your users will have to login again.
 * `ADMINS` will be used if you need to email informations to the site administrators.
 * `SQLALCHEMY_DATABASE_URI` and `DATABASE_CONNECT_OPTIONS` are SQLAlchemy connection options (hard to guess )