diff --git a/system/helpers/date_helper.php b/system/helpers/date_helper.php
index d328a7b..553e8d7 100644
--- a/system/helpers/date_helper.php
+++ b/system/helpers/date_helper.php
@@ -114,7 +114,7 @@
 		$formats = array(
 						'DATE_ATOM'		=>	'%Y-%m-%dT%H:%i:%s%Q',
 						'DATE_COOKIE'	=>	'%l, %d-%M-%y %H:%i:%s UTC',
-						'DATE_ISO8601'	=>	'%Y-%m-%dT%H:%i:%s%O',
+						'DATE_ISO8601'	=>	'%Y-%m-%dT%H:%i:%s%Q',
 						'DATE_RFC822'	=>	'%D, %d %M %y %H:%i:%s %O',
 						'DATE_RFC850'	=>	'%l, %d-%M-%y %H:%m:%i UTC',
 						'DATE_RFC1036'	=>	'%D, %d %M %y %H:%i:%s %O',
diff --git a/user_guide/changelog.html b/user_guide/changelog.html
index 0b060da..013468f 100644
--- a/user_guide/changelog.html
+++ b/user_guide/changelog.html
@@ -199,6 +199,7 @@
 	<li>Fixed a bug where multiple libraries could not be loaded by passing an array to load-&gt;library()</li>
 	<li>Fixed a bug in the html helper where too much white space was rendered between the src and alt tags in the img() function.</li>
 	<li>Fixed a bug in the profilers _compile_queries() function.</li>
+	<li>Fixed a bug in the date helper where the DATE_ISO8601 variable was returning an incorrectly formatted date string.</li>
 </ul>
 
 <h2>Version 1.7.2</h2>
diff --git a/user_guide/helpers/date_helper.html b/user_guide/helpers/date_helper.html
index e38d81a..59641a9 100644
--- a/user_guide/helpers/date_helper.html
+++ b/user_guide/helpers/date_helper.html
@@ -129,7 +129,7 @@
 	<tr>
 		<td>DATE_ISO8601</td>
 		<td>ISO-8601</td>
-		<td>2005-08-14T16:13:03+0000</td>
+		<td>2005-08-14T16:13:03+00:00</td>
 	</tr>
 	<tr>
 		<td>DATE_RFC822</td>