diff --git a/docs/manual/CoreTypes/mapper.html b/docs/manual/CoreTypes/mapper.html
index 359201b10..839ca9f0f 100644
--- a/docs/manual/CoreTypes/mapper.html
+++ b/docs/manual/CoreTypes/mapper.html
@@ -72,6 +72,7 @@ this separator, use <code>${file.separator}</code> instead.</p>
 <code>&lt;classpath&gt;</code>, as well - that is,
 a <a href="../using.html#path">path</a>-like structure.</p>
 <h3>The built-in mapper types are:</h3>
+<p>All built-in mappers are case-sensitive.</p>
 <h4><a name="identity-mapper">identity</a></h4>
 <p>The target file name is identical to the source file name. Both
 <code>to</code> and <code>from</code> will be ignored.</p>