diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Revision history for haskell-src-exts-simple
 
+## 1.21.0.1    -- 2019-09-13
+
+* support haskell-src-exts 1.21.1
+
 ## 1.21.0.0    -- 2019-04-27
 
 * support haskell-src-exts 1.21.0
diff --git a/haskell-src-exts-simple.cabal b/haskell-src-exts-simple.cabal
--- a/haskell-src-exts-simple.cabal
+++ b/haskell-src-exts-simple.cabal
@@ -1,5 +1,5 @@
 name:                haskell-src-exts-simple
-version:             1.21.0.0
+version:             1.21.1.0
 synopsis:            A simplified view on the haskell-src-exts AST
 description:
     This package provides a shim for haskell-src-exts (HSE), exposing the
diff --git a/src/Language/Haskell/Exts/Simple/Fixity.hs b/src/Language/Haskell/Exts/Simple/Fixity.hs
--- a/src/Language/Haskell/Exts/Simple/Fixity.hs
+++ b/src/Language/Haskell/Exts/Simple/Fixity.hs
@@ -16,8 +16,9 @@
 import Language.Haskell.Exts.Simple.Syntax
 import Language.Haskell.Exts.SrcLoc
 import Control.Monad
+import Control.Monad.Fail
 
 -- * Functions
 
-applyFixities :: (AppFixity ast, Functor ast, Monad m) => [Fixity] -> ast () -> m (ast ())
+applyFixities :: (AppFixity ast, Functor ast, MonadFail m) => [Fixity] -> ast () -> m (ast ())
 applyFixities fixs = liftM (fmap (const ())) . H.applyFixities fixs . fmap (const noSrcSpan)