diff --git a/Sound/Tidal/Parse.hs b/Sound/Tidal/Parse.hs
--- a/Sound/Tidal/Parse.hs
+++ b/Sound/Tidal/Parse.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE OverloadedStrings, TypeSynonymInstances, FlexibleInstances #-}
+{-# LANGUAGE OverloadedStrings, TypeSynonymInstances, FlexibleInstances, CPP #-}
 {-# LANGUAGE LambdaCase #-}
 
 module Sound.Tidal.Parse where
@@ -12,7 +12,7 @@
 import Data.Colour.SRGB
 import GHC.Exts( IsString(..) )
 import Data.Monoid
-import qualified Data.Semigroup as Sem
+-- import qualified Data.Semigroup as Sem
 import Control.Exception as E
 import Control.Applicative ((<$>), (<*>), pure)
 import Data.Maybe
@@ -21,6 +21,10 @@
 import Sound.Tidal.Pattern
 import Sound.Tidal.Time (Arc, Time)
 
+#ifdef TIDAL_SEMIGROUP
+import qualified Data.Semigroup as Sem
+#endif
+
 -- | AST representation of patterns
 
 data TPat a = TPat_Atom a
@@ -40,12 +44,18 @@
             | TPat_pE (TPat Int) (TPat Int) (TPat Integer) (TPat a)
             deriving (Show)
 
+#ifdef TIDAL_SEMIGROUP
 instance Sem.Semigroup (TPat a) where
   (<>) = TPat_Overlay
 
 instance Parseable a => Monoid (TPat a) where
    mempty = TPat_Silence
    mappend = (<>)
+#else
+instance Parseable a => Monoid (TPat a) where
+   mempty = TPat_Silence
+   mappend = TPat_Overlay
+#endif
 
 toPat :: Enumerable a => TPat a -> Pattern a
 toPat = \case
diff --git a/Sound/Tidal/Pattern.hs b/Sound/Tidal/Pattern.hs
--- a/Sound/Tidal/Pattern.hs
+++ b/Sound/Tidal/Pattern.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE DeriveDataTypeable, CPP #-}
 {-# OPTIONS_GHC -Wall -fno-warn-orphans -fno-warn-name-shadowing #-}
 
 module Sound.Tidal.Pattern where
@@ -23,7 +23,10 @@
 
 import Text.Show.Functions ()
 import qualified Control.Exception as E
+
+#ifdef TIDAL_SEMIGROUP
 import qualified Data.Semigroup as Sem
+#endif
 
 -- | The pattern datatype, a function from a time @Arc@ to @Event@
 -- values. For discrete patterns, this returns the events which are
@@ -162,14 +165,21 @@
                  (xs (s',e'))
                 )
 
+#ifdef TIDAL_SEMIGROUP
 -- | @mappend@ a.k.a. @<>@ is a synonym for @overlay@.
 instance Sem.Semigroup (Pattern a) where
   (<>) = overlay
 
--- | @mempty@ is a synonym for @silence@.
 instance Monoid (Pattern a) where
   mempty = silence
   mappend = (<>)
+
+#else
+-- | @mempty@ is a synonym for @silence@.
+instance Monoid (Pattern a) where
+  mempty = silence
+  mappend = overlay
+#endif
 
 instance Monad Pattern where
   return = pure
diff --git a/tests/test.hs b/tests/test.hs
--- a/tests/test.hs
+++ b/tests/test.hs
@@ -13,7 +13,8 @@
 main = defaultMain tests
 
 tests :: TestTree
-tests = testGroup "Tests" [basic1
+tests = testGroup "Tests" [basic1,
+                           parser1
                            -- patternsOfPatterns
                           ]
 
@@ -21,7 +22,12 @@
          [
            testCase "silence" $ same16 (fast 1.1 silence) (silence :: Pattern Double),
            testCase "fast" $ same16  silence (silence :: Pattern Double),
-           testCase "fast" $ same16 "bd*128" (rep 128 "bd")
+           testCase "fast2" $ same16 "bd*128" (rep 128 "bd")
+         ]
+
+parser1 = testGroup "subpatterns"
+         [
+           testCase "square" $ same16 ("bd sn" :: Pattern String) ("[bd sn]" :: Pattern String)
          ]
 
 patternsOfPatterns =
diff --git a/tidal.cabal b/tidal.cabal
--- a/tidal.cabal
+++ b/tidal.cabal
@@ -1,5 +1,5 @@
 name:                tidal
-version:             0.9.7
+version:             0.9.8
 synopsis:            Pattern language for improvised music
 -- description:
 homepage:            http://tidalcycles.org/
@@ -12,13 +12,16 @@
 category:            Sound
 build-type:          Simple
 cabal-version:       >=1.10
-tested-with:         GHC == 7.10.3, GHC == 8.0.1, GHC == 8.4.1
+tested-with:         GHC == 7.10.3, GHC == 8.0.1
 
 Extra-source-files: README.md CHANGELOG.md tidal.el doc/tidal.md
 
 Description: Tidal is a domain specific language for live coding pattern.
 
 library
+  if impl(ghc == 8.4.1)
+    cpp-options: -DTIDAL_SEMIGROUP
+
   default-language:    Haskell2010
 
   Exposed-modules:     Sound.Tidal.Bjorklund
@@ -55,7 +58,7 @@
     , websockets > 0.8
     , mtl >= 2.1
 
-  if !impl(ghc >= 8.0)
+  if !impl(ghc >= 8.4.1)
     build-depends: semigroups == 0.18.*
 
 source-repository head