diff --git a/wp-includes/classes.php b/wp-includes/classes.php
index ff1fb6acfc..58e6f2b09d 100644
--- a/wp-includes/classes.php
+++ b/wp-includes/classes.php
@@ -724,7 +724,7 @@ class retrospam_mgr {
 		foreach( $this->comment_list as $comment ) {
 			if( $comment->approved == 1 ) {
 				foreach( $this->spam_words as $word ) {
-					if ( empty( $word ) )
+					if ( empty( trim($word) ) )
 						continue;
 					$fulltext = strtolower($comment->email.' '.$comment->url.' '.$comment->ip.' '.$comment->text);
 					if( strpos( $fulltext, strtolower(trim($word)) ) != FALSE ) {