diff --git a/sql-words.cabal b/sql-words.cabal
--- a/sql-words.cabal
+++ b/sql-words.cabal
@@ -1,5 +1,5 @@
 name:                sql-words
-version:             0.1.6.2
+version:             0.1.6.3
 synopsis:            SQL keywords data constructors into OverloadedString
 description:         This package contiains SQL keywords constructors defined as
                      OverloadedString literals and helper functions to concate these.
@@ -8,11 +8,12 @@
 license-file:        LICENSE
 author:              Kei Hibino
 maintainer:          ex8k.hibino@gmail.com
-copyright:           Copyright (c) 2013-2018 Kei Hibino
+copyright:           Copyright (c) 2013-2019 Kei Hibino
 category:            Database
 build-type:          Simple
 cabal-version:       >=1.10
-tested-with:           GHC == 8.4.1, GHC == 8.4.2, GHC == 8.4.3
+tested-with:           GHC == 8.6.1, GHC == 8.6.2, GHC == 8.6.3, GHC == 8.6.4, GHC == 8.6.5
+                     , GHC == 8.4.1, GHC == 8.4.2, GHC == 8.4.3, GHC == 8.4.4
                      , GHC == 8.2.1, GHC == 8.2.2
                      , GHC == 8.0.1, GHC == 8.0.2
                      , GHC == 7.10.1, GHC == 7.10.2, GHC == 7.10.3
@@ -22,20 +23,22 @@
 
 library
   exposed-modules:
-                        Language.SQL.Keyword.Type
-                        Language.SQL.Keyword.Concat
-                        Language.SQL.Keyword
+                       Language.SQL.Keyword.Type
+                       Language.SQL.Keyword.Concat
+                       Language.SQL.Keyword
 
   other-modules:
-                        Language.SQL.Keyword.Internal.Type
+                       Language.SQL.Keyword.Internal.Type
 
-  build-depends:          base >=4.5 && <5
+  build-depends:         base >=4.5 && <5
   if impl(ghc < 8)
-    build-depends:        semigroups
-  hs-source-dirs:       src
-  ghc-options:          -Wall
+    build-depends:       semigroups
+  hs-source-dirs:      src
+  ghc-options:         -Wall
+  if impl(ghc >= 8)
+    ghc-options:         -Wcompat -Wnoncanonical-monadfail-instances
 
-  default-language:     Haskell2010
+  default-language:    Haskell2010
 
 test-suite monoids
   build-depends:         base >=4.5 && <5
@@ -48,8 +51,10 @@
 
   hs-source-dirs:      test
   ghc-options:         -Wall
+  if impl(ghc >= 8)
+    ghc-options:         -Wcompat -Wnoncanonical-monadfail-instances
 
-  default-language:     Haskell2010
+  default-language:    Haskell2010
 
 source-repository head
   type:       git
diff --git a/src/Language/SQL/Keyword/Internal/Type.hs b/src/Language/SQL/Keyword/Internal/Type.hs
--- a/src/Language/SQL/Keyword/Internal/Type.hs
+++ b/src/Language/SQL/Keyword/Internal/Type.hs
@@ -1,6 +1,6 @@
 -- |
 -- Module      : Language.SQL.Keyword.Internal.Type
--- Copyright   : 2013-2018 Kei Hibino
+-- Copyright   : 2013-2019 Kei Hibino
 -- License     : BSD3
 --
 -- Maintainer  : ex8k.hibino@gmail.com
@@ -55,7 +55,7 @@
 
 instance Monoid DString where
   mempty  = DString id
-  mappend = dappend
+  mappend = (<>)
 
 -- | Type represent SQL keywords.
 data Keyword = SELECT | ALL | DISTINCT | ON
@@ -150,7 +150,7 @@
 -- | 'Keyword' default concatination separate by space.
 instance Monoid Keyword where
   mempty  = fromDString mempty
-  mappend = kappend
+  mappend = (<>)
 
 
 -- | Show 'Keyword'