diff --git a/library/HTMLPurifier/AttrDef/Pixels.php b/library/HTMLPurifier/AttrDef/Pixels.php
index 652b4269..98a6e18f 100644
--- a/library/HTMLPurifier/AttrDef/Pixels.php
+++ b/library/HTMLPurifier/AttrDef/Pixels.php
@@ -19,7 +19,11 @@ class HTMLPurifier_AttrDef_Pixels extends HTMLPurifier_AttrDef
if ($int < 0) return '0';
- // could use some upper-bound checking
+ // upper-bound value, extremely high values can
+ // crash operating systems, see
+ // WARNING, above link WILL crash you if you're using Windows
+
+ if ($int > 1200) return '1200';
return (string) $int;