Document the other consequence of losing your key
diff --git a/docs/contributing.rst b/docs/contributing.rst
index cb9c728..036043f 100644
--- a/docs/contributing.rst
+++ b/docs/contributing.rst
@@ -244,7 +244,8 @@
    docs: commands succeeded
    congratulations :)
 
-The HTML documentation index can now be found at ``docs/_build/html/index.html``
+The HTML documentation index can now be found at
+``docs/_build/html/index.html``.
 
 
 .. _`GitHub`: https://github.com/pyca/cryptography
diff --git a/docs/fernet.rst b/docs/fernet.rst
index 241bf1e..3f0cdde 100644
--- a/docs/fernet.rst
+++ b/docs/fernet.rst
@@ -30,7 +30,9 @@
 
         Generates a fresh fernet key. Keep this some place safe! If you lose it
         you'll no longer be able to decrypt messages; if anyone else gains
-        access to it, they'll be able to decrypt all of your messages.
+        access to it, they'll be able to decrypt all of your messages, and
+        they'll also be able forge arbitrary messages which will be
+        authenticated and decrypted.
 
     .. method:: encrypt(plaintext)