diff --git a/src/Data/Unamb.hs b/src/Data/Unamb.hs
--- a/src/Data/Unamb.hs
+++ b/src/Data/Unamb.hs
@@ -41,10 +41,16 @@
 import Control.Concurrent
 import Control.Exception
 import Data.Typeable
-import Data.TagBits (unsafeIsEvaluated)
 
+-- Drop the unsafeIsEvaluated optimization for now.  See comments below.
+
+-- import Data.TagBits (unsafeIsEvaluated)
 -- import Data.IsEvaluated
 
+-- Temporary def until I know how to detect and handle evaluated-as-bottom values.
+unsafeIsEvaluated :: a -> Bool
+unsafeIsEvaluated = const False
+
 -- | Use a particular exception as our representation for waiting forever.
 data BothBottom = BothBottom deriving(Show,Typeable)
 
@@ -68,6 +74,18 @@
     | otherwise = unamb' a b
 {-# INLINE unamb #-}
 
+-- I want something like the following:
+
+-- unamb a b
+--     | unsafeIsEvaluated a = if isBottom a then b else a
+--     | unsafeIsEvaluated b = if isBottom b then a else b
+--     | otherwise = unamb' a b
+
+-- where isBottom assumes that its argument is recognizably evaluated
+-- (unsafeIsEvaluated yields True).  What does an evaluated bottom values
+-- look like in the RTS?
+
+
 -- | For use when we already know that neither argument is already evaluated
 unamb' :: a -> a -> a
 unamb' = (fmap.fmap) restartingUnsafePerformIO amb'
@@ -128,11 +146,15 @@
 
 -- | n-ary 'unamb'
 unambs :: [a] -> a
+unambs = foldr unamb undefined
+
+{-
 unambs []  = undefined
 unambs xs  = foldr1 unamb' xs `unamb'` foldr findEvaluated undefined xs
     where
         findEvaluated a b | unsafeIsEvaluated a = a
                           | otherwise = b
+-}
 
 -- | Ambiguous choice operator.  Yield either value.  Evaluates in
 -- separate threads and picks whichever finishes first.  See also
@@ -239,6 +261,9 @@
 a `asAgree` b = assuming (a == b) a
 {-# INLINE asAgree #-}
 
+-- Note: asAgree == flatGlb (from Data.Glb in lub package).
+-- Examine uses of asAgree,u and consider whether glb is a better fit.
+
 {--------------------------------------------------------------------
     Some useful special applications of 'unamb'
 --------------------------------------------------------------------}
@@ -345,6 +370,9 @@
 {-
 
 -- Examples:
+
+undefined `unamb` 3 :: Int
+3 `unamb` undefined :: Int
 
 undefined `por` True
 True `por` undefined
diff --git a/unamb.cabal b/unamb.cabal
--- a/unamb.cabal
+++ b/unamb.cabal
@@ -1,5 +1,5 @@
 Name:                unamb
-Version:             0.2.3
+Version:             0.2.4
 Cabal-Version:       >= 1.2
 Synopsis:            Unambiguous choice
 Category:            Concurrency, Data, Other
@@ -32,8 +32,10 @@
 Library
   hs-Source-Dirs:      src
   Extensions:
-  Build-Depends:       base >= 4 && < 5,
-                       tag-bits >= 0.1 && < 0.2
+  Build-Depends:       base >= 4 && < 5
+
+--                     , tag-bits >= 0.1.1 && < 0.2
+
   Exposed-Modules:     
                        Data.Unamb
   ghc-options:         -Wall