diff --git a/wp-includes/classes.php b/wp-includes/classes.php
index e6c960ddbc..1c1f49b7dd 100644
--- a/wp-includes/classes.php
+++ b/wp-includes/classes.php
@@ -679,6 +679,8 @@ class retrospam_mgr {
 		foreach( $this->comment_list as $comment ) {
 			if( $comment->approved == 1 ) {
 				foreach( $this->spam_words as $word ) {
+					if ( empty( $word ) )
+						continue;
 					$fulltext = strtolower($comment->email.' '.$comment->url.' '.$comment->ip.' '.$comment->text);
 					if( strpos( $fulltext, strtolower(trim($word)) ) != FALSE ) {
 						$this->found_comments[] = $comment->ID;