commit d621ae1603f27b3de867b46e5ad4d28460097dac
Author: Ollie Charles <ollie@ocharles.org.uk>
Date:   Wed Sep 18 14:52:34 2019 +0100

    Update Pure.hs

diff --git a/src/Codec/Crypto/RSA/Pure.hs b/src/Codec/Crypto/RSA/Pure.hs
index a69907d..e3513a9 100644
--- a/src/Codec/Crypto/RSA/Pure.hs
+++ b/src/Codec/Crypto/RSA/Pure.hs
@@ -111,8 +111,8 @@ instance Binary PrivateKey where
               d   <- os2ip `fmap` getLazyByteString (fromIntegral (public_size pub))
               return (PrivateKey pub d 0 0 0 0 0)
 
-failOnError :: (MonadFail m, Show a) => Either a b -> m b
-failOnError (Left e)  = fail (show e)
+failOnError :: (Monad m, Show a) => Either a b -> m b
+failOnError (Left e)  = error (show e)
 failOnError (Right b) = return b
 
 -- ----------------------------------------------------------------------------