diff --git a/system/helpers/date_helper.php b/system/helpers/date_helper.php
index 095e460..a82450a 100644
--- a/system/helpers/date_helper.php
+++ b/system/helpers/date_helper.php
@@ -442,7 +442,7 @@
 		$datestr = trim($datestr);
 		$datestr = preg_replace("/\040+/", "\040", $datestr);
 
-		if ( ! ereg("^[0-9]{2,4}\-[0-9]{1,2}\-[0-9]{1,2}\040[0-9]{1,2}:[0-9]{1,2}.*$", $datestr))
+		if ( ! preg_match('/^[0-9]{2,4}\-[0-9]{1,2}\-[0-9]{1,2}\s[0-9]{1,2}:[0-9]{1,2}(?::[0-9]{1,2})?(?:\s[AP]M)?$/i', $datestr))
 		{
 			return FALSE;
 		}
diff --git a/user_guide/changelog.html b/user_guide/changelog.html
index e0e2bef..207c594 100644
--- a/user_guide/changelog.html
+++ b/user_guide/changelog.html
@@ -67,6 +67,7 @@
 		<ul>
 			<li>Improved accuracy of calculations in <a href="helpers/number_helper.html">Number helper</a>.</li>
 			<li>Removed added newlines ("\n") from most form and html helper functions.</li>
+			<li>Tightened up validation in Date Helper human_to_unix(), and eliminated the POSIX regex.</li>
 		</ul>
 	</li>
 	<li>Other changes