diff --git a/lib/redcloth3.rb b/lib/redcloth3.rb
index c91c61718..ee934b6ab 100644
--- a/lib/redcloth3.rb
+++ b/lib/redcloth3.rb
@@ -505,7 +505,7 @@ class RedCloth3 < String
         atts
     end
 
-    STYLES_RE = /^(color|width|height|border|background|padding|margin|font|text)(-[a-z]+)*:\s*((\d+%?|\d+px|\d+(\.\d+)?em|#[0-9a-f]+|[a-z]+)\s*)+$/i
+    STYLES_RE = /^(color|width|height|border|background|padding|margin|font|text|float)(-[a-z]+)*:\s*((\d+%?|\d+px|\d+(\.\d+)?em|#[0-9a-f]+|[a-z]+)\s*)+$/i
 
     def sanitize_styles(str)
       styles = str.split(";").map(&:strip)