diff --git a/src/Synthesizer/MIDI/CausalIO/Process.hs b/src/Synthesizer/MIDI/CausalIO/Process.hs
--- a/src/Synthesizer/MIDI/CausalIO/Process.hs
+++ b/src/Synthesizer/MIDI/CausalIO/Process.hs
@@ -87,7 +87,7 @@
 
 import qualified Data.List.HT as ListHT
 import qualified Data.Maybe as Maybe
-import Data.Monoid (Monoid, mempty, mappend, )
+import Data.Monoid (Monoid, mempty)
 import Data.Semigroup (Semigroup, (<>), )
 import Data.Maybe (maybeToList, )
 import Data.Tuple.HT (mapFst, mapPair, )
@@ -296,7 +296,6 @@
 
 instance Monoid NoteOffList where
    mempty = NoteOffList (EventListTT.pause mempty)
-   mappend = (<>)
 
 {- |
 The function defined here are based on the interpretation
diff --git a/src/Synthesizer/MIDI/PiecewiseConstant/ControllerSet.hs b/src/Synthesizer/MIDI/PiecewiseConstant/ControllerSet.hs
--- a/src/Synthesizer/MIDI/PiecewiseConstant/ControllerSet.hs
+++ b/src/Synthesizer/MIDI/PiecewiseConstant/ControllerSet.hs
@@ -59,8 +59,8 @@
 import Control.Monad (liftM2, msum, )
 import Data.Traversable (traverse, )
 import Data.Foldable (traverse_, )
-import Data.Monoid (Monoid, mempty, mappend, )
-import Data.Semigroup (Semigroup, (<>), )
+import Data.Monoid (Monoid, mempty)
+import Data.Semigroup (Semigroup, (<>))
 
 import Data.Maybe.HT (toMaybe, )
 import Data.Tuple.HT (mapFst, mapPair, )
@@ -138,7 +138,6 @@
 
 instance Monoid (T key y) where
    mempty = Cons Map.empty (EventListTT.pause mempty)
-   mappend = (<>)
 
 instance (NFData key, NFData a) => CutG.NormalForm (T key a) where
    evaluateHead xs = rnf (initial xs)
diff --git a/synthesizer-midi.cabal b/synthesizer-midi.cabal
--- a/synthesizer-midi.cabal
+++ b/synthesizer-midi.cabal
@@ -1,5 +1,5 @@
 Name:           synthesizer-midi
-Version:        0.7
+Version:        0.7.0.1
 License:        GPL
 License-File:   LICENSE
 Author:         Henning Thielemann <haskell@henning-thielemann.de>
@@ -19,7 +19,7 @@
 Build-Type:     Simple
 
 Source-Repository this
-  Tag:         0.7
+  Tag:         0.7.0.1
   Type:        darcs
   Location:    http://code.haskell.org/synthesizer/midi/
 
@@ -27,9 +27,6 @@
   Type:        darcs
   Location:    http://code.haskell.org/synthesizer/midi/
 
-Flag splitBase
-  description: Choose the new smaller, split-up base package.
-
 Flag buildExamples
   Description: Build example executables
   Default:     False
@@ -52,14 +49,8 @@
     array >=0.1 && <0.6,
     transformers >=0.2 && <0.7,
     semigroups >=0.1 && <1,
-    utility-ht >=0.0.1 && <0.1
-
-  If flag(splitBase)
-    Build-Depends:
-      base >= 3 && <5
-  Else
-    Build-Depends:
-      base >= 1.0 && < 2
+    utility-ht >=0.0.1 && <0.1,
+    base >=4.11 && <5
 
   If impl(ghc>=7.0)
     GHC-Options: -fwarn-unused-do-bind