diff --git a/CHANGES.txt b/CHANGES.txt
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -1,5 +1,7 @@
 Changelog for Extra
 
+1.4.12
+    Add writeVar
 1.4.11
     Require QuickCheck 2.9
     #23, deprecate offsetTimeIncrease and subtract
diff --git a/extra.cabal b/extra.cabal
--- a/extra.cabal
+++ b/extra.cabal
@@ -1,7 +1,7 @@
 cabal-version:      >= 1.10
 build-type:         Simple
 name:               extra
-version:            1.4.11
+version:            1.4.12
 license:            BSD3
 license-file:       LICENSE
 category:           Development
diff --git a/src/Control/Concurrent/Extra.hs b/src/Control/Concurrent/Extra.hs
--- a/src/Control/Concurrent/Extra.hs
+++ b/src/Control/Concurrent/Extra.hs
@@ -19,7 +19,7 @@
     -- * Lock
     Lock, newLock, withLock, withLockTry,
     -- * Var
-    Var, newVar, readVar, modifyVar, modifyVar_, withVar,
+    Var, newVar, readVar, writeVar, modifyVar, modifyVar_, withVar,
     -- * Barrier
     Barrier, newBarrier, signalBarrier, waitBarrier, waitBarrierMaybe,
     ) where
@@ -178,6 +178,10 @@
 -- | Read the current value of the 'Var'.
 readVar :: Var a -> IO a
 readVar (Var x) = readMVar x
+
+-- | Write a value to become the new value of 'Var'.
+writeVar :: Var a -> a -> IO ()
+writeVar v x = modifyVar_ v $ const $ return x
 
 -- | Modify a 'Var' producing a new value and a return result.
 modifyVar :: Var a -> (a -> IO (a, b)) -> IO b
diff --git a/src/Extra.hs b/src/Extra.hs
--- a/src/Extra.hs
+++ b/src/Extra.hs
@@ -8,7 +8,7 @@
 module Extra(
     -- * Control.Concurrent.Extra
     -- | Extra functions available in @"Control.Concurrent.Extra"@.
-    getNumCapabilities, setNumCapabilities, withNumCapabilities, forkFinally, once, onceFork, Lock, newLock, withLock, withLockTry, Var, newVar, readVar, modifyVar, modifyVar_, withVar, Barrier, newBarrier, signalBarrier, waitBarrier, waitBarrierMaybe,
+    getNumCapabilities, setNumCapabilities, withNumCapabilities, forkFinally, once, onceFork, Lock, newLock, withLock, withLockTry, Var, newVar, readVar, writeVar, modifyVar, modifyVar_, withVar, Barrier, newBarrier, signalBarrier, waitBarrier, waitBarrierMaybe,
     -- * Control.Exception.Extra
     -- | Extra functions available in @"Control.Exception.Extra"@.
     retry, retryBool, showException, stringException, errorIO, displayException, ignore, catch_, handle_, try_, catchJust_, handleJust_, tryJust_, catchBool, handleBool, tryBool,