diff --git a/phpBB/docs/CHANGELOG.html b/phpBB/docs/CHANGELOG.html
index b691f19015..e75ccb5f42 100644
--- a/phpBB/docs/CHANGELOG.html
+++ b/phpBB/docs/CHANGELOG.html
@@ -94,6 +94,7 @@
 		<li>[Fix] Quote bbcode fixes. Letting parse quote=&quot;[&quot; and re-allowing whitelisted bbcodes within username portion (Bug #14770)</li>
 		<li>[Sec] Fix bbcode helpline display for custom bbcodes - this requires style changes for any custom style (Bug #14850)</li>
 		<li>[Fix] Correctly count announcements when filtering forums by date (Bug #14877)</li>
+		<li>[Fix] Allow charset names containing underscores or spaces</li>
 	</ul>
 
 	<a name="v30rc6"></a><h3>1.ii. Changes since 3.0.RC6</h3>
diff --git a/phpBB/includes/utf/utf_tools.php b/phpBB/includes/utf/utf_tools.php
index 77971f7e68..e7f144af51 100644
--- a/phpBB/includes/utf/utf_tools.php
+++ b/phpBB/includes/utf/utf_tools.php
@@ -768,7 +768,7 @@ function utf8_recode($string, $encoding)
 	}
 
 	// If nothing works, check if we have a custom transcoder available
-	if (!preg_match('#^[a-z0-9\\-]+$#', $encoding))
+	if (!preg_match('#^[a-z0-9_ \\-]+$#', $encoding))
 	{
 		// Make sure the encoding name is alphanumeric, we don't want it to be abused into loading arbitrary files
 		trigger_error('Unknown encoding: ' . $encoding, E_USER_ERROR);