diff --git a/phpBB/includes/search/base.php b/phpBB/includes/search/base.php
index f691bc942f..b364dead9a 100644
--- a/phpBB/includes/search/base.php
+++ b/phpBB/includes/search/base.php
@@ -294,7 +294,7 @@ class phpbb_search_base
 			$sql_where = '';
 			foreach ($authors as $author)
 			{
-				$sql_where .= (($sql_where) ? ' OR ' : '') . 'search_authors LIKE \'% ' . (int) $author . ' %\'';
+				$sql_where .= (($sql_where) ? ' OR ' : '') . 'search_authors ' . $db->sql_like_expression($db->any_char . ' ' . (int) $author . ' ' . $db->any_char);
 			}
 
 			$sql = 'SELECT search_key
diff --git a/phpBB/includes/search/fulltext_mysql.php b/phpBB/includes/search/fulltext_mysql.php
index 5372cfac7b..99467da978 100644
--- a/phpBB/includes/search/fulltext_mysql.php
+++ b/phpBB/includes/search/fulltext_mysql.php
@@ -708,7 +708,7 @@ class phpbb_search_fulltext_mysql extends phpbb_search_base
 	*/
 	function index_remove($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 b9085695ac..59d6a312b3 100644
--- a/phpBB/includes/search/fulltext_native.php
+++ b/phpBB/includes/search/fulltext_native.php
@@ -1335,7 +1335,7 @@ class phpbb_search_fulltext_native extends phpbb_search_base
 			$db->sql_query($sql);
 		}
 
-		$this->destroy_cache(array_unique($word_texts), $author_ids);
+		$this->destroy_cache(array_unique($word_texts), array_unique($author_ids));
 	}
 
 	/**