diff --git a/include/strip.php b/include/strip.php
index a313eb3..8c49b7d 100644
--- a/include/strip.php
+++ b/include/strip.php
@@ -55,8 +55,8 @@ function insertstrip(&$strip) {
 function updatestrip(&$strip) {
 	global $dbConnection;
 
-	$strip->book = ($strip->book === '') ? 'NULL' : (int)$strip->book;
-	$strip->page = ($strip->page === '') ? 'NULL' : (int)$strip->page;
+	$strip->book = ($strip->book === '') ? NULL : (int)$strip->book;
+	$strip->page = ($strip->page === '') ? NULL : (int)$strip->page;
 
 	$dbConnection->beginTransaction();