diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,9 @@
+concurrent-output (1.10.19) unstable; urgency=medium
+
+  * Support building for WASM.
+
+ -- Joey Hess <id@joeyh.name>  Wed, 30 Aug 2023 16:03:03 -0400
+
 concurrent-output (1.10.18) unstable; urgency=medium
 
   * Avoid some build warnings on Windows.
diff --git a/System/Console/Regions.hs b/System/Console/Regions.hs
--- a/System/Console/Regions.hs
+++ b/System/Console/Regions.hs
@@ -126,17 +126,19 @@
 import Control.Concurrent.STM.TSem
 import Control.Concurrent.Async
 import System.Console.ANSI
-import qualified System.Console.Terminal.Size as Console
 import System.IO
 import System.IO.Unsafe (unsafePerformIO)
 import Text.Read
 import Data.List (intercalate, nubBy)
+import Control.Applicative
+import Prelude
+#ifdef VERSION_terminal_size
+import qualified System.Console.Terminal.Size as Console
 #ifndef mingw32_HOST_OS
 import System.Posix.Signals
 import System.Posix.Signals.Exts
 #endif
-import Control.Applicative
-import Prelude
+#endif
 
 import System.Console.Concurrent
 import Utility.Monad
@@ -182,22 +184,26 @@
 regionList :: TMVar [ConsoleRegion]
 regionList = unsafePerformIO newEmptyTMVarIO
 
--- | On Unix systems, this TVar is automatically updated when the
--- terminal is resized. On Windows, it is only initialized on program start
--- with the current terminal size.
+data ConsoleSize = ConsoleSize
+	{ _consoleHeight :: Int
+	, _consoleWidth :: Int
+	}
+
 {-# NOINLINE consoleSize #-}
-consoleSize :: TVar (Console.Window Int)
-consoleSize = unsafePerformIO $ newTVarIO $ 
-	Console.Window { Console.width = 80, Console.height = 25}
+consoleSize :: TVar ConsoleSize
+consoleSize = unsafePerformIO $ newTVarIO $
+	ConsoleSize { _consoleWidth = 80, _consoleHeight = 25}
 
 type Width = Int
 
 -- | Gets the width of the console.
 --
 -- On Unix, this is automatically updated when the terminal is resized.
--- On Windows, it is only initialized on program start.
+-- On Windows, it is determined at start. On WASM,
+-- the console width is hard coded to 80 since WASI does not provide a way
+-- to determine it.
 consoleWidth :: STM Int
-consoleWidth = munge . Console.width <$> readTVar consoleSize
+consoleWidth = munge . _consoleWidth <$> readTVar consoleSize
   where
 #ifndef mingw32_HOST_OS
 	munge = id
@@ -208,8 +214,13 @@
 #endif
 
 -- | Get the height of the console.
+--
+-- On Unix, this is automatically updated when the terminal is resized.
+-- On Windows, it is determined at start. On WASM,
+-- the console heigth is hard coded to 25 since WASI does not provide a way
+-- to determine it.
 consoleHeight :: STM Int
-consoleHeight = Console.height <$> readTVar consoleSize
+consoleHeight = _consoleHeight <$> readTVar consoleSize
 
 -- | Check if `displayConsoleRegions` is running.
 regionDisplayEnabled :: IO Bool
@@ -453,11 +464,20 @@
 			installResizeHandler Nothing
 
 trackConsoleWidth :: IO ()
+#ifdef VERSION_terminal_size
 trackConsoleWidth = do
-	let getsz = maybe noop (atomically . writeTVar consoleSize)
+	let getsz = maybe noop (atomically . writeTVar consoleSize . conv)
 		=<< Console.size
 	getsz
 	installResizeHandler (Just getsz)
+  where
+	conv wsz = ConsoleSize
+		{ _consoleWidth = Console.width wsz
+		, _consoleHeight = Console.height wsz
+		}
+#else
+trackConsoleWidth = return ()
+#endif
 
 data DisplayChange
 	= BufferChange BufferSnapshot 
@@ -694,8 +714,12 @@
 
 installResizeHandler :: Maybe (IO ()) -> IO ()
 #ifndef mingw32_HOST_OS
+#ifdef VERSION_terminal_size
 installResizeHandler h = void $
 	installHandler windowChange (maybe Default Catch h) Nothing
+#else
+installResizeHandler _ = return ()
+#endif
 #else
 installResizeHandler _ = return ()
 #endif
diff --git a/concurrent-output.cabal b/concurrent-output.cabal
--- a/concurrent-output.cabal
+++ b/concurrent-output.cabal
@@ -1,5 +1,5 @@
 Name: concurrent-output
-Version: 1.10.18
+Version: 1.10.19
 Cabal-Version: >= 1.10
 License: BSD2
 Maintainer: Joey Hess <id@joeyh.name>
@@ -40,7 +40,6 @@
     , transformers (>= 0.3.0 && < 0.7.0)
     , exceptions (>= 0.6.0 && < 0.11.0)
     , ansi-terminal (>= 0.6.2 && < 1.1.0)
-    , terminal-size (>= 0.3.0 && < 0.4.0)
   Exposed-Modules:
     System.Console.Concurrent
     System.Console.Concurrent.Internal
@@ -52,6 +51,8 @@
 
   if (! os(Windows))
     Build-Depends: unix (>= 2.7.0 && < 2.9.0)
+  if (! arch(wasm32))
+    Build-Depends: terminal-size (>= 0.3.0 && < 0.4.0)
 
 source-repository head
   type: git
diff --git a/demo2.hs b/demo2.hs
--- a/demo2.hs
+++ b/demo2.hs
@@ -1,21 +1,16 @@
 import Control.Concurrent.Async
 import Control.Concurrent
-import System.Console.Concurrent
 import System.Console.Regions
-import System.Console.Terminal.Size
-import qualified Data.Text as T
-import Control.Concurrent.STM
-import Control.Applicative
-import Data.Time.Clock
 import Control.Monad
 
-main = displayConsoleRegions $ mapConcurrently id
+main :: IO ()
+main = displayConsoleRegions $ void $ mapConcurrently id
 	[ spinner 100 1 "Pinwheels!!" setConsoleRegion "/-\\|" (withtitle 1)
 	, spinner 100 1 "Bubbles!!!!" setConsoleRegion ".oOo." (withtitle 1)
 	, spinner 100 1 "Dots......!" appendConsoleRegion "."  (const (take 3))
 	, spinner  30 2 "KleisiFish?" setConsoleRegion "  <=<   <=<  " (withtitle 10)
 	, spinner  10 9 "Countdowns!" setConsoleRegion
-		(reverse [1..10])
+		(reverse ([1..10] :: [Int]))
 		(\t n -> t ++ show (head n))
 	]
   where