diff --git a/lib/loofah/html5/scrub.rb b/lib/loofah/html5/scrub.rb
index 9f268e1d..82e6b099 100644
--- a/lib/loofah/html5/scrub.rb
+++ b/lib/loofah/html5/scrub.rb
@@ -6,7 +6,7 @@ module HTML5 # :nodoc:
     module Scrub
 
       CONTROL_CHARACTERS = /[`\u0000-\u0020\u007f\u0080-\u0101]/
-      CSS_KEYWORDISH = /\A(#[0-9a-f]+|rgb\(\d+%?,\d*%?,?\d*%?\)?|-?\d{0,2}\.?\d{0,2}(cm|em|ex|in|mm|pc|pt|px|%|,|\))?)\z/
+      CSS_KEYWORDISH = /\A(#[0-9a-f]+|rgb\(\d+%?,\d*%?,?\d*%?\)?|-?\d{0,3}\.?\d{0,10}(cm|em|ex|in|mm|pc|pt|px|%|,|\))?)\z/
       CRASS_SEMICOLON = {:node => :semicolon, :raw => ";"}
 
       class << self