diff --git a/src/ui/public/field_editor/field_editor.html b/src/ui/public/field_editor/field_editor.html
index 590d15154981a..ddee0fa140b7a 100644
--- a/src/ui/public/field_editor/field_editor.html
+++ b/src/ui/public/field_editor/field_editor.html
@@ -146,6 +146,19 @@ <h4>
           Painless is powerful but easy to use. It provides access to many <a target="_window" ng-href="{{editor.docLinks.painlessApi}}">native Java APIs <i class="fa-link fa"></i></a>. Read up on its <a target="_window" ng-href="{{editor.docLinks.painlessSyntax}}">syntax <i class="fa-link fa"></i></a> and you'll be up to speed in no time!
         </p>
 
+        <p>
+          Kibana currently imposes one special limitation on the scripts you write. Your scripts must consist of a single expression. Multi-statement scripts with an explicit return statement will not work.
+          In other words, the above example is a valid script, but something like the following is not.
+        </p>
+
+        <p>
+          <strong>Invalid</strong><br/>
+          <code>
+            def myField = doc['some_field'].value;<br/>
+            return myField;
+          </code>
+        </p>
+
         <p>
           Coming from an older version of Kibana? The <a target="_window" ng-href="{{editor.docLinks.luceneExpressions}}">Lucene Expressions <i class="fa-link fa"></i></a> you know and love are still available. Lucene expressions are a lot like JavaScript, but limited to basic arithmetic, bitwise and comparison operations.
         </p>