diff --git a/phpBB/includes/acp/acp_styles.php b/phpBB/includes/acp/acp_styles.php
index e0fb1459c2..c9ef818a67 100644
--- a/phpBB/includes/acp/acp_styles.php
+++ b/phpBB/includes/acp/acp_styles.php
@@ -2176,10 +2176,10 @@ parse_css_file = {PARSE_CSS_FILE}
 			$style_default = request_var('style_default', 0);
 			$store_db = request_var('store_db', 0);
 
-			$sql = "SELECT {$mode}_id
+			$sql = "SELECT {$mode}_id, {$mode}_name
 				FROM $sql_from
 				WHERE {$mode}_id <> $style_id
-				AND {$mode}_name = '" . $db->sql_escape(strtolower($name)) . "'";
+				AND LOWER({$mode}_name) = '" . $db->sql_escape(strtolower($name)) . "'";
 			$result = $db->sql_query($sql);
 			$conflict = $db->sql_fetchrow($result);
 			$db->sql_freeresult($result);
@@ -3206,7 +3206,7 @@ parse_css_file = {PARSE_CSS_FILE}
 		{
 			$sql = "SELECT {$mode}_id, {$mode}_name, {$mode}_path, {$mode}_storedb
 				FROM $sql_from
-				WHERE {$mode}_name = '" . $db->sql_escape(strtolower($cfg_data['inherit_from'])) . "'
+				WHERE {$mode}_name = '" . $db->sql_escape($cfg_data['inherit_from']) . "'
 					AND {$mode}_inherits_id = 0";
 			$result = $db->sql_query($sql);
 			$row = $db->sql_fetchrow($result);