diff --git a/src/BaconQrCode/Encoder/MaskUtil.php b/src/BaconQrCode/Encoder/MaskUtil.php
index c294d55..b0cb547 100644
--- a/src/BaconQrCode/Encoder/MaskUtil.php
+++ b/src/BaconQrCode/Encoder/MaskUtil.php
@@ -220,7 +220,7 @@ class MaskUtil
                 break;
 
             case 4:
-                $intermediate = (BitUtils::unsignedRightShift($y, 1) + ($x / 3)) & 0x1;
+                $intermediate = (BitUtils::unsignedRightShift($y, 1) + (int) ($x / 3)) & 0x1;
                 break;
 
             case 5: