diff --git a/silently.cabal b/silently.cabal
--- a/silently.cabal
+++ b/silently.cabal
@@ -1,5 +1,5 @@
 name: silently
-version: 1.2.4
+version: 1.2.4.1
 cabal-version: >= 1.8
 build-type: Simple
 license: BSD3
@@ -48,7 +48,7 @@
   type:
       exitcode-stdio-1.0
   ghc-options:
-      -Wall -threaded
+      -Wall -Werror -threaded
   hs-source-dirs:
       test
   build-depends:
@@ -65,6 +65,8 @@
       exitcode-stdio-1.0
   ghc-options:
       -Wall -threaded
+      -- FIXME: use -Werror
+      -- -Wall -Werror -threaded
   hs-source-dirs:
       src
     , test
diff --git a/src/System/IO/Silently.hs b/src/System/IO/Silently.hs
--- a/src/System/IO/Silently.hs
+++ b/src/System/IO/Silently.hs
@@ -12,7 +12,13 @@
 ) where
 
 import Prelude
+
+#if __GLASGOW_HASKELL__ >= 612
 import GHC.IO.Handle (hDuplicate, hDuplicateTo)
+#else
+import GHC.Handle (hDuplicate, hDuplicateTo)
+#endif
+
 import System.IO
 import qualified Control.Exception as E
 import Control.DeepSeq