diff --git a/docs/config.rst b/docs/config.rst
index 0397da6e..81e580ca 100644
--- a/docs/config.rst
+++ b/docs/config.rst
@@ -437,6 +437,7 @@ methods on the config object as well to load from individual files.  For a
 complete reference, read the :class:`~flask.Config` object's
 documentation.
 
+
 Configuring from Environment Variables
 --------------------------------------
 
@@ -448,15 +449,13 @@ Environment variables can be set on Linux or OS X with the export command in
 the shell before starting the server::
 
     $ export SECRET_KEY='5f352379324c22463451387a0aec5d2f'
-    $ export DEBUG=False
+    $ export MAIL_ENABLED=false
     $ python run-app.py
      * Running on http://127.0.0.1:5000/
-     * Restarting with reloader...
 
-On Windows systems use the `set` builtin instead::
+On Windows systems use the ``set`` builtin instead::
 
     >set SECRET_KEY='5f352379324c22463451387a0aec5d2f'
-    >set DEBUG=False
 
 While this approach is straightforward to use, it is important to remember that
 environment variables are strings -- they are not automatically deserialized
@@ -464,17 +463,15 @@ into Python types.
 
 Here is an example of a configuration file that uses environment variables::
 
-    # Example configuration
     import os
 
-    ENVIRONMENT_DEBUG = os.environ.get("DEBUG", default=False)
-    if ENVIRONMENT_DEBUG.lower() in ("f", "false"):
-        ENVIRONMENT_DEBUG = False
+    _mail_enabled = os.environ.get("MAIL_ENABLED", default="true")
+    MAIL_ENABLED = _mail_enabled.lower() in {"1", "t", "true"}
+
+    SECRET_KEY = os.environ.get("SECRET_KEY")
 
-    DEBUG = ENVIRONMENT_DEBUG
-    SECRET_KEY = os.environ.get("SECRET_KEY", default=None)
     if not SECRET_KEY:
-        raise ValueError("No secret key set for Flask application")
+        raise ValueError("No SECRET_KEY set for Flask application")
 
 
 Notice that any value besides an empty string will be interpreted as a boolean
@@ -486,6 +483,7 @@ ability to access the configuration when starting up.  There are other methods
 on the config object as well to load from individual files.  For a complete
 reference, read the :class:`~flask.Config` class documentation.
 
+
 Configuration Best Practices
 ----------------------------