diff --git a/src/Data/StorableVector.hs b/src/Data/StorableVector.hs
--- a/src/Data/StorableVector.hs
+++ b/src/Data/StorableVector.hs
@@ -242,7 +242,6 @@
 
 instance (Storable a) => Monoid (Vector a) where
     mempty  = empty
-    mappend = append
     mconcat = concat
 
 instance (Storable a, QC.Arbitrary a) => QC.Arbitrary (Vector a) where
diff --git a/src/Data/StorableVector/Lazy.hs b/src/Data/StorableVector/Lazy.hs
--- a/src/Data/StorableVector/Lazy.hs
+++ b/src/Data/StorableVector/Lazy.hs
@@ -163,7 +163,6 @@
 
 instance (Storable a) => Monoid (Vector a) where
     mempty  = empty
-    mappend = append
     mconcat = concat
 
 instance (Storable a, Eq a) => Eq (Vector a) where
@@ -207,7 +206,6 @@
 
 instance Monoid ChunkSize where
    mempty = ChunkSize 0
-   mappend (ChunkSize x) (ChunkSize y) = ChunkSize (x+y)
    mconcat = ChunkSize . sum . List.map (\(ChunkSize c) -> c)
 
 instance NonNeg.C ChunkSize where
diff --git a/src/Data/StorableVector/Lazy/Builder.hs b/src/Data/StorableVector/Lazy/Builder.hs
--- a/src/Data/StorableVector/Lazy/Builder.hs
+++ b/src/Data/StorableVector/Lazy/Builder.hs
@@ -23,7 +23,7 @@
 import Data.StorableVector.Lazy (ChunkSize, )
 import Control.Monad (liftM2, )
 import Control.Monad.ST.Strict (ST, runST, )
-import Data.Monoid (Monoid(mempty, mappend), )
+import Data.Monoid (Monoid(mempty), )
 import Data.Semigroup (Semigroup((<>)), )
 
 import Foreign.Storable (Storable, )
@@ -65,9 +65,7 @@
 
 instance Storable a => Monoid (Builder a) where
    {-# INLINE mempty #-}
-   {-# INLINE mappend #-}
    mempty = Builder (\_ -> id)
-   mappend = (<>)
 
 
 {- |
diff --git a/src/Data/StorableVector/Lazy/Typed.hs b/src/Data/StorableVector/Lazy/Typed.hs
--- a/src/Data/StorableVector/Lazy/Typed.hs
+++ b/src/Data/StorableVector/Lazy/Typed.hs
@@ -104,7 +104,7 @@
 import Data.Function.HT (compose2)
 import Data.Tuple.HT (mapPair, mapFst, mapSnd)
 import Data.Maybe.HT (toMaybe)
-import Data.Monoid (Monoid, mempty, mappend, mconcat)
+import Data.Monoid (Monoid, mempty, mconcat)
 import Data.Semigroup (Semigroup, (<>), )
 import Data.Either (Either)
 import Data.Maybe (Maybe(Just))
@@ -187,7 +187,6 @@
 
 instance (Size size, Storable a) => Monoid (Vector size a) where
     mempty  = empty
-    mappend = append
     mconcat = concat
 
 instance (Size size, Storable a, Eq a) => Eq (Vector size a) where
diff --git a/storablevector.cabal b/storablevector.cabal
--- a/storablevector.cabal
+++ b/storablevector.cabal
@@ -1,6 +1,6 @@
 Cabal-Version:       2.2
 Name:                storablevector
-Version:             0.2.13.3
+Version:             0.2.13.4
 Category:            Data
 Synopsis:            Fast, packed, strict storable arrays with a list interface like ByteString
 Description:
@@ -34,13 +34,7 @@
   foreign-ptr/slow/Data/StorableVector/Memory.hs
   foreign-ptr/jhc/Data/StorableVector/Memory.hs
 
-Flag splitBase
-  description: Choose the new smaller, split-up base package.
 
-Flag separateSYB
-  description: Data.Generics available in separate package.
-
-
 Source-Repository head
   type:     darcs
   location: http://code.haskell.org/storablevector/
@@ -48,7 +42,7 @@
 Source-Repository this
   type:     darcs
   location: http://code.haskell.org/storablevector/
-  tag:      0.2.13.3
+  tag:      0.2.13.4
 
 
 Library
@@ -68,16 +62,9 @@
       base >=1 && <2
   Else
     Hs-Source-Dirs: foreign-ptr/slow
-    If flag(splitBase)
-      If flag(separateSYB)
-        Build-Depends:
-          base >=4 && <5,
-          syb >=0.1 && <0.8
-      Else
-        Build-Depends:
-          base >=3 && <4
-    Else
-      Build-Depends: base >=1 && <2
+    Build-Depends:
+      base >=4.11 && <5,
+      syb >=0.1 && <0.8
 
   GHC-Options:         -Wall -funbox-strict-fields
   Default-Language:    Haskell98
@@ -122,13 +109,9 @@
     storablevector,
     bytestring >=0.9 && <0.13,
     utility-ht >=0.0.5 && <0.1,
-    QuickCheck >=1 && <3
-  If flag(splitBase)
-    Build-Depends:
-      random >=1.0 && <1.4,
-      base >=3 && <5
-  Else
-    Build-Depends:     base >=1.0 && <2
+    QuickCheck >=1 && <3,
+    random >=1.0 && <1.4,
+    base >=4 && <5
 
 Benchmark speedtest
   Type:                exitcode-stdio-1.0
@@ -144,11 +127,8 @@
     utility-ht,
     sample-frame >=0.0.1 && <0.1,
     unsafe,
-    deepseq
-  If flag(splitBase)
-    Build-Depends:   base >= 3 && <5
-  Else
-    Build-Depends:   base >= 1.0 && < 2
+    deepseq,
+    base >=4 && <5
 
 Benchmark speedpointer
   Type:                exitcode-stdio-1.0
@@ -158,8 +138,5 @@
   Hs-Source-Dirs:      speedtest
   Build-Depends:
     storablevector,
-    utility-ht
-  If flag(splitBase)
-    Build-Depends:   base >=3 && <5
-  Else
-    Build-Depends:   base >=1.0 && <2
+    utility-ht,
+    base >=4 && <5