diff --git a/Data/Time/LocalTime/TimeZone/Olson.hs b/Data/Time/LocalTime/TimeZone/Olson.hs
--- a/Data/Time/LocalTime/TimeZone/Olson.hs
+++ b/Data/Time/LocalTime/TimeZone/Olson.hs
@@ -1,7 +1,7 @@
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Time.LocalTime.TimeZone.Olson
--- Copyright   :  Yitzchak Gale 2010
+-- Copyright   :  Yitzchak Gale 2018
 --
 -- Maintainer  :  Yitzchak Gale <gale@sefer.org>
 -- Portability :  portable
@@ -13,7 +13,7 @@
 -- converting the parsed data into @TimeZoneSeries@ and @TimeZone@
 -- objects.
 
-{- Copyright (c) 2010 Yitzchak Gale. All rights reserved.
+{- Copyright (c) 2018 Yitzchak Gale. All rights reserved.
 For licensing information, see the BSD3-style license in the file
 LICENSE that was originally distributed by the author together with
 this file. -}
diff --git a/Data/Time/LocalTime/TimeZone/Olson/Parse.hs b/Data/Time/LocalTime/TimeZone/Olson/Parse.hs
--- a/Data/Time/LocalTime/TimeZone/Olson/Parse.hs
+++ b/Data/Time/LocalTime/TimeZone/Olson/Parse.hs
@@ -3,7 +3,7 @@
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Time.LocalTime.TimeZone.Olson.Parse
--- Copyright   :  Yitzchak Gale 2010
+-- Copyright   :  Yitzchak Gale 2018
 --
 -- Maintainer  :  Yitzchak Gale <gale@sefer.org>
 -- Portability :  portable
@@ -14,7 +14,7 @@
 -- <http://www.twinsun.com/tz/tz-link.htm>. Functions are provided for
 -- converting the parsed data into 'TimeZoneSeries' objects.
 
-{- Copyright (c) 2010 Yitzchak Gale. All rights reserved.
+{- Copyright (c) 2018 Yitzchak Gale. All rights reserved.
 For licensing information, see the BSD3-style license in the file
 LICENSE that was originally distributed by the author together with
 this file. -}
diff --git a/Data/Time/LocalTime/TimeZone/Olson/Render.hs b/Data/Time/LocalTime/TimeZone/Olson/Render.hs
--- a/Data/Time/LocalTime/TimeZone/Olson/Render.hs
+++ b/Data/Time/LocalTime/TimeZone/Olson/Render.hs
@@ -2,7 +2,7 @@
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Time.LocalTime.TimeZone.Olson.Render
--- Copyright   :  Yitzchak Gale 2010
+-- Copyright   :  Yitzchak Gale 2018
 --
 -- Maintainer  :  Yitzchak Gale <gale@sefer.org>
 -- Portability :  portable
@@ -12,7 +12,7 @@
 -- Unix-like systems. For more information about this format, see
 -- <http://www.twinsun.com/tz/tz-link.htm>.
 
-{- Copyright (c) 2010 Yitzchak Gale. All rights reserved.
+{- Copyright (c) 2018ZZ Yitzchak Gale. All rights reserved.
 For licensing information, see the BSD3-style license in the file
 LICENSE that was originally distributed by the author together with
 this file. -}
diff --git a/Data/Time/LocalTime/TimeZone/Olson/Types.hs b/Data/Time/LocalTime/TimeZone/Olson/Types.hs
--- a/Data/Time/LocalTime/TimeZone/Olson/Types.hs
+++ b/Data/Time/LocalTime/TimeZone/Olson/Types.hs
@@ -1,8 +1,9 @@
 {-# OPTIONS_HADDOCK hide #-}
+{-# LANGUAGE CPP #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Time.LocalTime.TimeZone.Olson.Types
--- Copyright   :  Yitzchak Gale 2010
+-- Copyright   :  Yitzchak Gale 2018
 --
 -- Maintainer  :  Yitzchak Gale <gale@sefer.org>
 -- Portability :  portable
@@ -14,7 +15,7 @@
 --
 -- Both Version 1 and Version 2 timezone data can be represented.
 
-{- Copyright (c) 2010 Yitzchak Gale. All rights reserved.
+{- Copyright (c) 2018 Yitzchak Gale. All rights reserved.
 For licensing information, see the BSD3-style license in the file
 LICENSE that was originally distributed by the author together with
 this file. -}
@@ -36,6 +37,9 @@
 )
 where
 
+#if MIN_VERSION_base(4,11,0)
+import Data.Semigroup (Semigroup(..))
+#endif
 import Data.Monoid (Monoid(..))
 import Control.Monad (mplus)
 
@@ -71,13 +75,25 @@
     }
   deriving (Eq, Show)
 
+#if MIN_VERSION_base(4,11,0)
+instance Semigroup OlsonData where
+  OlsonData a  b  c  d <> OlsonData a' b' c' d' =
+      OlsonData (a ++ map (shiftBy $ length b) a')
+                (b ++ b') (c ++ c') (d `mplus` d')
+    where
+      shiftBy n trans = trans {transIndex = n + transIndex trans}
+
 instance Monoid OlsonData where
   mempty = OlsonData [] [] [] Nothing
+#else
+instance Monoid OlsonData where
+  mempty = OlsonData [] [] [] Nothing
   mappend (OlsonData a  b  c  d ) (OlsonData a' b' c' d') =
       OlsonData (a ++ map (shiftBy $ length b) a')
                 (b ++ b') (c ++ c') (d `mplus` d')
     where
       shiftBy n trans = trans {transIndex = n + transIndex trans}
+#endif
 
 -- | A @Transition@ represents a moment when the clocks change in a
 -- timezone. It consists of a Unix timestamp value that indicates the
diff --git a/LICENSE b/LICENSE
--- a/LICENSE
+++ b/LICENSE
@@ -1,4 +1,4 @@
-Copyright (c) 2010-2015 Yitzchak Gale. All rights reserved.
+Copyright (c) 2010-2018 Yitzchak Gale. All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -19,7 +19,7 @@
 package for a way to include timezone informaton from a binary Olson
 timezone file at compile time.
 
-Copyright (c) 2010-2015 Yitzchak Gale. All rights reserved.
+Copyright (c) 2010-2018 Yitzchak Gale. All rights reserved.
 
 For licensing information, see the BSD3-style license in the file
 LICENSE that was originally distributed by the author together with
diff --git a/timezone-olson.cabal b/timezone-olson.cabal
--- a/timezone-olson.cabal
+++ b/timezone-olson.cabal
@@ -1,5 +1,5 @@
 Name:                timezone-olson
-Version:             0.1.8
+Version:             0.1.9
 Synopsis:            A pure Haskell parser and renderer for binary Olson timezone files
 Description:         A parser and renderer for binary Olson timezone
                      files whose format is specified by the tzfile(5)
@@ -20,11 +20,13 @@
 License-file:        LICENSE
 Author:              Yitzchak Gale
 Maintainer:          yitz@sefer.org
-Copyright:           Copyright (c) 2010-2015 Yitzchak Gale. All rights reserved.
+Copyright:           Copyright (c) 2010-2018 Yitzchak Gale. All rights reserved.
 Category:            Data
 Build-type:          Simple
 Extra-source-files:  README.md, catTZ.hs, hzdump.hs
 Cabal-version:       >=1.10
+Tested-with:         GHC > 8.0 && < 8.5
+
 Source-repository HEAD
   type:              git
   location:          https://github.com/ygale/timezone-olson.git
@@ -37,7 +39,7 @@
                     , Data.Time.LocalTime.TimeZone.Olson.Types
   Build-depends:       base >= 3.0 && < 5.0,
                        timezone-series >= 0.1.0 && < 0.2,
-                       time >= 1.6 && < 1.9,
+                       time >= 1.6 && < 1.10,
                        binary >= 0.4.1 && < 0.9,
                        bytestring >= 0.9 && < 1.0,
                        extensible-exceptions >= 0.1.0 && < 0.2
