diff --git a/lucene/site/xsl/index.xsl b/lucene/site/xsl/index.xsl
index f729eca10de..f0d2d904101 100644
--- a/lucene/site/xsl/index.xsl
+++ b/lucene/site/xsl/index.xsl
@@ -65,7 +65,7 @@
             <li><a href="changes/Changes.html">Changes</a>: List of changes in this release.</li>
             <li><a href="MIGRATE.html">Migration Guide</a>: What changed in Lucene 4; how to migrate code from Lucene 3.x.</li>
             <li><a href="JRE_VERSION_MIGRATION.html">JRE Version Migration</a>: Information about upgrading between major JRE versions.</li>
-            <li><a href="core/org/apache/lucene/codecs/lucene40/package-summary.html#package_description">File Formats</a>: Guide to the index format used by Lucene.</li>
+            <li><a href="core/org/apache/lucene/codecs/lucene40/package-summary.html#package_description">File Formats</a>: Guide to the supported index format used by Lucene.  This can be customized by using <a href="core/org/apache/lucene/codecs/package-summary.html#package_description">an alternate codec</a>.</li>
             <li><a href="core/org/apache/lucene/search/package-summary.html#package_description">Search and Scoring in Lucene</a>: Introduction to how Lucene scores documents.</li>
             <li><a href="core/org/apache/lucene/search/similarities/TFIDFSimilarity.html">Classic Scoring Formula</a>: Formula of Lucene's classic <a href="http://en.wikipedia.org/wiki/Vector_Space_Model">Vector Space</a> implementation. (look <a href="core/org/apache/lucene/search/similarities/package-summary.html#package_description">here</a> for other models)</li>
             <li><a href="queryparser/org/apache/lucene/queryparser/classic/package-summary.html#package_description">Classic QueryParser Syntax</a>: Overview of the Classic QueryParser's syntax and features.</li>