1 files changed, 4 insertions, 1 deletions
diff --git a/compiler/parser/Lexer.x b/compiler/parser/Lexer.x
index c64c0173e8..c4d0d4d127 100644
--- a/compiler/parser/Lexer.x
+++ b/compiler/parser/Lexer.x
@@ -41,6 +41,7 @@
 -- Alex "Haskell code fragment top"
 
 {
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE BangPatterns #-}
 {-# LANGUAGE LambdaCase #-}
 
@@ -2015,9 +2016,11 @@ instance Applicative P where
 
 instance Monad P where
   (>>=) = thenP
+#if !MIN_VERSION_base(4,13,0)
   fail = MonadFail.fail
+#endif
 
-instance MonadFail P where
+instance MonadFail.MonadFail P where
   fail = failP
 
 returnP :: a -> P a