diff --git a/src/Data/TimeMap.hs b/src/Data/TimeMap.hs
--- a/src/Data/TimeMap.hs
+++ b/src/Data/TimeMap.hs
@@ -59,7 +59,7 @@
 import qualified Focus                    as F
 import qualified ListT                    as L
 import Control.Monad (forM)
-import Control.Concurrent.STM
+import Control.Concurrent.STM (STM, atomically, TVar, writeTVar, readTVar, modifyTVar', modifyTVar, newTVar)
 
 
 data TimeIndexed a = TimeIndexed
diff --git a/src/Data/TimeSet.hs b/src/Data/TimeSet.hs
new file mode 100644
--- /dev/null
+++ b/src/Data/TimeSet.hs
@@ -0,0 +1,71 @@
+module Data.TimeSet where
+
+import Data.TimeMap (TimeMap, newTimeMap)
+import qualified Data.TimeMap as TimeMap
+import Data.Hashable (Hashable (..))
+import Data.Time (UTCTime, NominalDiffTime, addUTCTime, diffUTCTime, getCurrentTime)
+import qualified Data.HashSet             as HS
+import Control.Concurrent.STM (STM)
+
+
+newtype TimeSet a = TimeSet {getTimeSet :: TimeMap a ()}
+
+
+newTimeSet :: STM (TimeSet a)
+newTimeSet = TimeSet <$> newTimeMap
+
+
+insert :: (Hashable a, Eq a) => a -> TimeSet a -> IO ()
+insert a (TimeSet xs) = TimeMap.insert a () xs
+
+
+insertWithTime :: (Hashable a, Eq a) => UTCTime -> a -> TimeSet a -> STM ()
+insertWithTime t a (TimeSet xs) = TimeMap.insertWithTime t a () xs
+
+
+elem :: (Hashable a, Eq a) => a -> TimeSet a -> STM Bool
+elem a (TimeSet xs) = do
+  r <- TimeMap.lookup a xs
+  case r of
+    Nothing -> pure False
+    Just () -> pure True
+
+
+elems :: (Hashable a, Eq a) => TimeSet a -> STM (HS.HashSet a)
+elems (TimeSet xs) = TimeMap.keys xs
+
+
+size :: TimeSet a -> STM Int
+size (TimeSet xs) = TimeMap.size xs
+
+
+null :: TimeSet a -> STM Bool
+null (TimeSet xs) = TimeMap.null xs
+
+
+timeOf :: (Hashable a, Eq a) => a -> TimeSet a -> STM (Maybe UTCTime)
+timeOf a (TimeSet xs) = TimeMap.timeOf a xs
+
+
+ageOf :: (Hashable a, Eq a) => a -> TimeSet a -> IO (Maybe NominalDiffTime)
+ageOf a (TimeSet xs) = TimeMap.ageOf a xs
+
+
+delete :: (Hashable a, Eq a) => a -> TimeSet a -> STM ()
+delete a (TimeSet xs) = TimeMap.delete a xs
+
+
+touch :: (Hashable a, Eq a) => a -> TimeSet a -> IO ()
+touch a (TimeSet xs) = TimeMap.touch a xs
+
+
+filter :: (Hashable a, Eq a) => (a -> Bool) -> TimeSet a -> STM ()
+filter f (TimeSet xs) = TimeMap.filterWithKey (\k _ -> f k) xs
+
+
+filterSince :: (Hashable a, Eq a) => UTCTime -> TimeSet a -> STM ()
+filterSince t (TimeSet xs) = TimeMap.filterSince t xs
+
+
+filterFromNow :: (Hashable a, Eq a) => NominalDiffTime -> TimeSet a -> IO ()
+filterFromNow t (TimeSet xs) = TimeMap.filterFromNow t xs
diff --git a/timemap.cabal b/timemap.cabal
--- a/timemap.cabal
+++ b/timemap.cabal
@@ -1,5 +1,5 @@
 Name:                   timemap
-Version:                0.0.4
+Version:                0.0.5
 Author:                 Athan Clark <athan.clark@gmail.com>
 Maintainer:             Athan Clark <athan.clark@gmail.com>
 License:                BSD3
@@ -19,6 +19,7 @@
   HS-Source-Dirs:       src
   GHC-Options:          -Wall
   Exposed-Modules:      Data.TimeMap
+                        Data.TimeSet
   Other-Modules:        Data.TimeMap.Internal
   Build-Depends:        base >= 4.8 && < 5
                       , containers