diff --git a/docs/patterns/mongokit.rst b/docs/patterns/mongokit.rst
index 7d87221a..b8a6ecfb 100644
--- a/docs/patterns/mongokit.rst
+++ b/docs/patterns/mongokit.rst
@@ -54,7 +54,8 @@ Here is an example document (put this also into :file:`app.py`, e.g.)::
         def validate(value):
             if len(value) <= length:
                 return True
-            raise ValidationError('%s must be at most {0} characters long'.format(length))
+            # must have %s in error format string to have mongokit place key in there
+            raise ValidationError('%s must be at most {} characters long'.format(length))
         return validate
 
     class User(Document):
@@ -76,9 +77,7 @@ Here is an example document (put this also into :file:`app.py`, e.g.)::
 
 This example shows you how to define your schema (named structure), a
 validator for the maximum character length and uses a special MongoKit feature
-called `use_dot_notation`.  When you define a ValidationError, you can add the `%s`
-into the format string to have the value placed in there for the final error message.
-ValueErrors can also be thrown as an alternative. Per default MongoKit behaves like a python
+called `use_dot_notation`.  Per default MongoKit behaves like a python
 dictionary but with `use_dot_notation` set to ``True`` you can use your
 documents like you use models in nearly any other ORM by using dots to
 separate between attributes.