diff --git a/org.jacoco.doc/docroot/doc/ant.html b/org.jacoco.doc/docroot/doc/ant.html
index 8fccda1..41ccf9f 100644
--- a/org.jacoco.doc/docroot/doc/ant.html
+++ b/org.jacoco.doc/docroot/doc/ant.html
@@ -31,6 +31,12 @@
   creates with the <a href="#report"><code>report</code></a> task.  
 </p>
 
+<p class="hint">
+  If you want to have line number information included in the coverage reports
+  or you want source code highlighting the class files of the test target must
+  be compiled with debug information. 
+</p>
+
 <h2>Example</h2>
 
 <p>