diff --git a/gi-gtk-declarative-app-simple.cabal b/gi-gtk-declarative-app-simple.cabal
--- a/gi-gtk-declarative-app-simple.cabal
+++ b/gi-gtk-declarative-app-simple.cabal
@@ -1,5 +1,5 @@
 name:                 gi-gtk-declarative-app-simple
-version:              0.4.0
+version:              0.4.1
 synopsis:             Declarative GTK+ programming in Haskell in the style of Pux.
 description:          Experimental application architecture in the style of
                       PureScript Pux, built on top of gi-gtk-declarative.
@@ -26,7 +26,6 @@
                       , gi-gobject              >= 2      && <3
                       , gi-glib
                       , gi-gtk                  >= 3      && <4
-                      , gi-gtk-declarative      >= 0.1.0  && <2
                       , gi-gdk
                       , haskell-gi              >= 0.21   && <0.22
                       , haskell-gi-base         >= 0.21   && <0.22
@@ -34,6 +33,7 @@
                       , pipes                   >= 4      && <5
                       , pipes-concurrency       >= 2      && <3
                       , text
+                      , gi-gtk-declarative      >= 0.4  && <0.5
   hs-source-dirs:       src
   default-language:     Haskell2010
   ghc-options:          -Wall
diff --git a/src/GI/Gtk/Declarative/App/Simple.hs b/src/GI/Gtk/Declarative/App/Simple.hs
--- a/src/GI/Gtk/Declarative/App/Simple.hs
+++ b/src/GI/Gtk/Declarative/App/Simple.hs
@@ -26,6 +26,8 @@
 import           GI.Gtk.Declarative.State
 import           Pipes
 import           Pipes.Concurrent
+import           System.Exit
+import           System.IO
 
 -- | Describes an state reducer application.
 data App window state event =
@@ -72,6 +74,7 @@
   => App window state event      -- ^ Application to run
   -> IO state
 run app = do
+  assertRuntimeSupportsBoundThreads
   void $ Gtk.init Nothing
   Async.withAsync (runLoop app <* Gtk.mainQuit) $ \lastState -> do
     Gtk.main
@@ -92,7 +95,10 @@
 --       Gtk.mainQuit
 --     Gtk.main
 -- @
-runLoop :: (Typeable event, Gtk.IsWindow window, Gtk.IsBin window) => App window state event -> IO state
+runLoop
+  :: (Typeable event, Gtk.IsWindow window, Gtk.IsBin window)
+  => App window state event
+  -> IO state
 runLoop App {..} = do
   let firstMarkup = view initialState
   events                  <- newChan
@@ -138,6 +144,17 @@
           -- Finally, we loop.
           loop newState newMarkup events sub newModel
         Exit -> return oldModel
+
+-- | Assert that the program was linked using the @-threaded@ flag, to
+-- enable the threaded runtime required by this module.
+assertRuntimeSupportsBoundThreads :: IO ()
+assertRuntimeSupportsBoundThreads =
+  unless rtsSupportsBoundThreads $ do
+    hPutStrLn stderr "GI.Gtk.Declarative.App.Simple requires the program to \
+                     \be linked using the threaded runtime of GHC (-threaded \
+                     \flag)."
+    exitFailure
+
 
 publishEvent :: Chan event -> event -> IO ()
 publishEvent mvar = void . writeChan mvar