diff --git a/lib/loofah/html5/whitelist.rb b/lib/loofah/html5/whitelist.rb
index 467c1d6d..4898f4b9 100644
--- a/lib/loofah/html5/whitelist.rb
+++ b/lib/loofah/html5/whitelist.rb
@@ -635,6 +635,8 @@ module WhiteList
                                           "silver",
                                           "solid",
                                           "teal",
+                                          "thin",
+                                          "thick",
                                           "top",
                                           "transparent",
                                           "underline",