diff --git a/phpBB/index.php b/phpBB/index.php
index 079dfc8509..46d2c0bd9d 100644
--- a/phpBB/index.php
+++ b/phpBB/index.php
@@ -209,6 +209,7 @@ if( ( $total_categories = count($category_rows) ) )
 		FROM " . AUTH_ACCESS_TABLE . " aa, " . USER_GROUP_TABLE . " ug, " . GROUPS_TABLE . " g, " . USERS_TABLE . " u
 		WHERE aa.auth_mod = " . TRUE . " 
 			AND g.group_single_user = 1
+			AND g.group_type <> " . GROUP_HIDDEN . "
 			AND ug.group_id = aa.group_id 
 			AND g.group_id = aa.group_id 
 			AND u.user_id = ug.user_id 
@@ -229,6 +230,7 @@ if( ( $total_categories = count($category_rows) ) )
 		FROM " . AUTH_ACCESS_TABLE . " aa, " . USER_GROUP_TABLE . " ug, " . GROUPS_TABLE . " g 
 		WHERE aa.auth_mod = " . TRUE . " 
 			AND g.group_single_user = 0
+			AND g.group_type != " . GROUP_HIDDEN . "
 			AND ug.group_id = aa.group_id 
 			AND g.group_id = aa.group_id 
 		GROUP BY g.group_id, g.group_name, aa.forum_id 
@@ -436,4 +438,4 @@ $template->pparse("body");
 
 include($phpbb_root_path . 'includes/page_tail.'.$phpEx);
 
-?>
\ No newline at end of file
+?>
diff --git a/phpBB/viewforum.php b/phpBB/viewforum.php
index 1e5d183966..4ab4b1b174 100644
--- a/phpBB/viewforum.php
+++ b/phpBB/viewforum.php
@@ -190,6 +190,7 @@ $sql = "SELECT u.user_id, u.username
 	WHERE aa.forum_id = $forum_id 
 		AND aa.auth_mod = " . TRUE . " 
 		AND g.group_single_user = 1
+		AND g.group_type <> ". GROUP_HIDDEN ."
 		AND ug.group_id = aa.group_id 
 		AND g.group_id = aa.group_id 
 		AND u.user_id = ug.user_id 
@@ -211,6 +212,7 @@ $sql = "SELECT g.group_id, g.group_name
 	WHERE aa.forum_id = $forum_id
 		AND aa.auth_mod = " . TRUE . " 
 		AND g.group_single_user = 0
+		AND g.group_type <> ". GROUP_HIDDEN ."
 		AND ug.group_id = aa.group_id 
 		AND g.group_id = aa.group_id 
 	GROUP BY g.group_id, g.group_name  
@@ -669,4 +671,4 @@ $template->pparse("body");
 //
 include($phpbb_root_path . 'includes/page_tail.'.$phpEx);
 
-?>
\ No newline at end of file
+?>