diff --git a/phpBB/includes/search/fulltext_mysql.php b/phpBB/includes/search/fulltext_mysql.php
index 29cdd8ee9a..52372a14d8 100644
--- a/phpBB/includes/search/fulltext_mysql.php
+++ b/phpBB/includes/search/fulltext_mysql.php
@@ -707,7 +707,7 @@ class fulltext_mysql extends search_backend
 	*/
 	function index_remove($post_ids, $author_ids, $forum_ids)
 	{
-		$this->destroy_cache(array(), $author_ids);
+		$this->destroy_cache(array(), array_unique($author_ids));
 	}
 
 	/**
diff --git a/phpBB/includes/search/fulltext_native.php b/phpBB/includes/search/fulltext_native.php
index 727e3aaffb..b63205fd76 100644
--- a/phpBB/includes/search/fulltext_native.php
+++ b/phpBB/includes/search/fulltext_native.php
@@ -1334,7 +1334,7 @@ class fulltext_native extends search_backend
 			$db->sql_query($sql);
 		}
 
-		$this->destroy_cache(array_unique($word_texts), $author_ids);
+		$this->destroy_cache(array_unique($word_texts), array_unique($author_ids));
 	}
 
 	/**