diff --git a/Codec/TPTP/Base.hs b/Codec/TPTP/Base.hs
--- a/Codec/TPTP/Base.hs
+++ b/Codec/TPTP/Base.hs
@@ -17,6 +17,7 @@
 
 import Codec.TPTP.QuickCheck
 import Control.Applicative
+import Control.Monad
 import Control.Monad.Identity
 import Control.Monad.State
 import Data.Data
diff --git a/Codec/TPTP/Diff.hs b/Codec/TPTP/Diff.hs
--- a/Codec/TPTP/Diff.hs
+++ b/Codec/TPTP/Diff.hs
@@ -20,6 +20,7 @@
 import Codec.TPTP.Base
 import Codec.TPTP.Pretty
 import Text.PrettyPrint.ANSI.Leijen
+import Control.Monad
 import Control.Monad.Identity
 
 
diff --git a/Codec/TPTP/Export.hs b/Codec/TPTP/Export.hs
--- a/Codec/TPTP/Export.hs
+++ b/Codec/TPTP/Export.hs
@@ -13,7 +13,7 @@
 
 -- | Convenient wrapper for 'toTPTP'
 toTPTP' :: forall a. (ToTPTP a) => a -> String
-toTPTP' = ($"") . toTPTP
+toTPTP' = ($ "") . toTPTP
 
 s :: String -> String -> String
 s = showString
diff --git a/changelog.markdown b/changelog.markdown
--- a/changelog.markdown
+++ b/changelog.markdown
@@ -1,3 +1,9 @@
+## 0.5.1.0
+
+* Fix compilation error with `mtl >=2.3`
+* Fix an `-Woperator-whitespace-ext-conflict` warning
+* Fix cabal warnings
+
 ## 0.5.0.0
 
 * Add `GFormulaTerm` constructor to `GData` and support `$fot` `formula_data` (#1, #2, #19, thanks to @agomezl)
diff --git a/logic-TPTP.cabal b/logic-TPTP.cabal
--- a/logic-TPTP.cabal
+++ b/logic-TPTP.cabal
@@ -1,6 +1,6 @@
 name: logic-TPTP
-version: 0.5.0.0
-cabal-version: >= 1.8
+version: 0.5.1.0
+cabal-version: >= 1.10
 build-type: Simple
 license: GPL
 license-file: LICENSE
@@ -37,13 +37,14 @@
 extra-source-files: testing/compileTests.sh
                     changelog.markdown
 
-tested-with: GHC==8.8.2
-tested-with: GHC==8.6.4
-tested-with: GHC==8.4.4
-tested-with: GHC==8.2.2
-tested-with: GHC==8.0.2
-tested-with: GHC==7.10.3
-tested-with: GHC==7.8.4
+tested-with: GHC==9.8.2
+tested-with: GHC==9.6.6
+tested-with: GHC==9.4.8
+tested-with: GHC==9.2.8
+tested-with: GHC==9.0.2
+tested-with: GHC==8.10.7
+tested-with: GHC==8.8.4
+tested-with: GHC==8.6.5
 
 source-repository head
  type: git
@@ -63,7 +64,7 @@
                    , array
                    , syb
                    , containers
-                   , ansi-wl-pprint
+                   , ansi-wl-pprint < 1.0
                    , QuickCheck >= 2
                    , mtl
                    , pointed
@@ -86,6 +87,7 @@
                   , Util
 
  build-tools: alex >= 3.1.1, happy >= 1.19.1
+ default-language:  Haskell2010
 
 
 Executable TestImportExportImportFile
@@ -96,11 +98,12 @@
  build-depends:     logic-TPTP
                   , base
                   , ansi-wl-pprint
-                  , optparse-applicative >=0.11 && <0.16
+                  , optparse-applicative >=0.11 && <0.19
                   , pcre-light
                   , semigroups
  if impl(ghc <7.10)
   build-depends:    pcre-light <0.4.1
+ default-language:  Haskell2010
  other-extensions:  CPP
  if !flag(BuildTestPrograms)
   buildable: False
@@ -120,6 +123,7 @@
                   , transformers-compat >= 0.5
  if impl(ghc <7.10)
   build-depends:    pcre-light <0.4.1
+ default-language:  Haskell2010
  other-extensions:  CPP
 
 Executable PrettyPrintFile
@@ -140,6 +144,7 @@
                   , syb
  if impl(ghc <7.10)
   build-depends:    pcre-light <0.4.1
+ default-language:  Haskell2010
  other-extensions:  CPP
  if !flag(BuildTestPrograms)
   buildable: False
@@ -162,6 +167,7 @@
                   , syb
  if impl(ghc <7.10)
   build-depends:    pcre-light <0.4.1
+ default-language:  Haskell2010
  other-extensions:  CPP
  if !flag(BuildTestPrograms)
   buildable: False