diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,10 @@
 # CHANGELOG
 
+- 0.9.1.0 (2018-04-26)
+    * Support GHC 8.4.1 by adding instance SemiGroup ImportPortion (by George
+      Wilson)
+    * Bump `aeson` to 1.3
+
 - 0.9.0.2 (2018-01-03)
     * Bump lower bound of `directory` to `1.2.3` for `getXdgDirectory`
 
diff --git a/README.markdown b/README.markdown
--- a/README.markdown
+++ b/README.markdown
@@ -149,6 +149,15 @@
 [ide-haskell]: https://atom.io/packages/ide-haskell
 [atom-beautify]: Https://atom.io/packages/atom-beautify
 
+Using with Continuous Integration
+---------------------------------
+
+You can quickly grab the latest binary and run `stylish-haskell` like so:
+
+    curl -sL https://raw.github.com/jaspervdj/stylish-haskell/master/scripts/latest.sh | sh -s .
+
+Where the `.` can be replaced with the arguments you pass to `stylish-haskell`.
+
 Credits
 -------
 
diff --git a/lib/Language/Haskell/Stylish/Step/Imports.hs b/lib/Language/Haskell/Stylish/Step/Imports.hs
--- a/lib/Language/Haskell/Stylish/Step/Imports.hs
+++ b/lib/Language/Haskell/Stylish/Step/Imports.hs
@@ -22,9 +22,9 @@
 import           Data.List                       (intercalate, sortBy)
 import qualified Data.Map                        as M
 import           Data.Maybe                      (isJust, maybeToList)
-import           Data.Monoid                     ((<>))
 import           Data.Ord                        (comparing)
 import qualified Data.Set                        as S
+import           Data.Semigroup                  (Semigroup ((<>)))
 import qualified Language.Haskell.Exts           as H
 
 
@@ -168,10 +168,13 @@
   = ImportSome [H.CName l]  -- ^ @A(x, y, z)@
   | ImportAll               -- ^ @A(..)@
 
+instance Ord l => Semigroup (ImportPortion l) where
+  ImportSome a <> ImportSome b = ImportSome (setUnion a b)
+  _ <> _                       = ImportAll
+
 instance Ord l => Monoid (ImportPortion l) where
   mempty = ImportSome []
-  mappend (ImportSome a) (ImportSome b) = ImportSome (setUnion a b)
-  mappend _ _                           = ImportAll
+  mappend = (<>)
 
 -- | O(n log n) union.
 setUnion :: Ord a => [a] -> [a] -> [a]
diff --git a/stylish-haskell.cabal b/stylish-haskell.cabal
--- a/stylish-haskell.cabal
+++ b/stylish-haskell.cabal
@@ -1,5 +1,5 @@
 Name:          stylish-haskell
-Version:       0.9.0.2
+Version:       0.9.1.0
 Synopsis:      Haskell code prettifier
 Homepage:      https://github.com/jaspervdj/stylish-haskell
 License:       BSD3
@@ -48,7 +48,7 @@
     Paths_stylish_haskell
 
   Build-depends:
-    aeson            >= 0.6    && < 1.3,
+    aeson            >= 0.6    && < 1.4,
     base             >= 4.8    && < 5,
     bytestring       >= 0.9    && < 0.11,
     containers       >= 0.3    && < 0.6,
@@ -57,6 +57,7 @@
     file-embed       >= 0.0.10 && < 0.1,
     haskell-src-exts >= 1.18   && < 1.21,
     mtl              >= 2.0    && < 2.3,
+    semigroups       >= 0.18   && < 0.19,
     syb              >= 0.3    && < 0.8,
     yaml             >= 0.7    && < 0.9
 
@@ -70,7 +71,7 @@
     strict               >= 0.3  && < 0.4,
     optparse-applicative >= 0.12 && < 0.15,
     -- Copied from regular dependencies...
-    aeson            >= 0.6    && < 1.3,
+    aeson            >= 0.6    && < 1.4,
     base             >= 4.8    && < 5,
     bytestring       >= 0.9    && < 0.11,
     containers       >= 0.3    && < 0.6,