diff --git a/user_guide/libraries/validation.html b/user_guide/libraries/validation.html
index f9cac85..facd1a5 100644
--- a/user_guide/libraries/validation.html
+++ b/user_guide/libraries/validation.html
@@ -602,6 +602,12 @@
 <td class="td">Returns FALSE if the supplied IP is not valid.</td>
 <td class="td">&nbsp;</td>
 </tr>
+<tr>
+    <td class="td"><strong>valid_base64</strong></td>
+    <td class="td">No</td>
+    <td class="td">Returns FALSE if the supplied string contains anything other than valid Base64 characters.</td>
+    <td class="td">&nbsp;</td>
+</tr>
 </table>
 
 <p><strong>Note:</strong> These rules can also be called as discreet functions. For example:</p>