diff --git a/lambdabot-haskell-plugins.cabal b/lambdabot-haskell-plugins.cabal
--- a/lambdabot-haskell-plugins.cabal
+++ b/lambdabot-haskell-plugins.cabal
@@ -1,11 +1,11 @@
 name:                   lambdabot-haskell-plugins
-version:                5.3
+version:                5.3.0.2
 
 license:                GPL
 license-file:           LICENSE
 
 author:                 Don Stewart
-maintainer:             James Cook <mokus@deepbondi.net>
+maintainer:             Bertram Felgenhauer <int-e@gmx.de>
 
 category:               Development, Web
 synopsis:               Lambdabot Haskell plugins
@@ -46,7 +46,7 @@
 
 build-type:             Simple
 cabal-version:          >= 1.10
-tested-with:            GHC == 8.2.2, GHC == 8.4.4, GHC == 8.6.5, GHC == 8.8.3
+tested-with:            GHC == 8.2.2, GHC == 8.4.4, GHC == 8.6.5, GHC == 8.8.4, GHC == 8.10.4
 
 extra-source-files:     src/Lambdabot/Plugin/Haskell/Free/Test.hs
 
diff --git a/src/Lambdabot/Plugin/Haskell/UnMtl.hs b/src/Lambdabot/Plugin/Haskell/UnMtl.hs
--- a/src/Lambdabot/Plugin/Haskell/UnMtl.hs
+++ b/src/Lambdabot/Plugin/Haskell/UnMtl.hs
@@ -137,6 +137,7 @@
     [ ("Cont",     lift2 $ \r       a -> (a -->      r) -->      r)
     , ("ContT",    lift3 $ \r     m a -> (a --> m $$ r) --> m $$ r)
     , ("ErrorT",   lift3 $ \e     m a -> m $$ (con "Either" $$ e $$ a))
+    , ("ExceptT",  lift3 $ \e     m a -> m $$ (con "Either" $$ e $$ a))
     , ("Identity", lift1 $ \        a -> a)
     , ("ListT",    lift2 $ \      m a -> m $$ (return list_tycon $$ a))
     , ("RWS",      lift4 $ \r w s   a -> r --> s -->      tuple [a, s, w])