diff --git a/extra/math/functions/functions.factor b/extra/math/functions/functions.factor
index 59ade44365..85e07fe73f 100755
--- a/extra/math/functions/functions.factor
+++ b/extra/math/functions/functions.factor
@@ -34,6 +34,10 @@ M: real sqrt
 : set-bit ( x n -- y ) 2^ bitor ; foldable
 : bit-clear? ( x n -- ? ) 2^ bitand zero? ; foldable
 : bit-set? ( x n -- ? ) bit-clear? not ; foldable
+: unmask ( x n -- ? ) bitnot bitand ; foldable
+: unmask? ( x n -- ? ) unmask 0 > ; foldable
+: mask ( x n -- ? ) bitand ; foldable
+: mask? ( x n -- ? ) mask 0 > ; foldable
 
 GENERIC: (^) ( x y -- z ) foldable