diff --git a/index.html b/index.html
index 745311283..ca2ec79ba 100644
--- a/index.html
+++ b/index.html
@@ -1049,7 +1049,7 @@ _.isString("moe");
       <p id="isNumber">
         <b class="header">isNumber</b><code>_.isNumber(object)</code>
         <br />
-        Returns <i>true</i> if <b>object</b> is a Number.
+        Returns <i>true</i> if <b>object</b> is a Number (including <tt>NaN</tt>).
       </p>
       <pre>
 _.isNumber(8.4 * 5);