diff --git a/.travis.yml b/.travis.yml
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,16 +1,108 @@
-language: haskell
+# This file has been generated -- see https://github.com/hvr/multi-ghc-travis
+language: c
+sudo: false
+
+cache:
+  directories:
+    - $HOME/.cabsnap
+    - $HOME/.cabal/packages
+
+before_cache:
+  - rm -fv $HOME/.cabal/packages/hackage.haskell.org/build-reports.log
+  - rm -fv $HOME/.cabal/packages/hackage.haskell.org/00-index.tar
+
+matrix:
+  include:
+    - env: CABALVER=1.18 GHCVER=7.4.2
+      compiler: ": #GHC 7.4.2"
+      addons: {apt: {packages: [cabal-install-1.18,ghc-7.4.2,hlint], sources: [hvr-ghc]}}
+    - env: CABALVER=1.18 GHCVER=7.6.3
+      compiler: ": #GHC 7.6.3"
+      addons: {apt: {packages: [cabal-install-1.18,ghc-7.6.3,hlint], sources: [hvr-ghc]}}
+    - env: CABALVER=1.18 GHCVER=7.8.4
+      compiler: ": #GHC 7.8.4"
+      addons: {apt: {packages: [cabal-install-1.18,ghc-7.8.4,hlint], sources: [hvr-ghc]}}
+    - env: CABALVER=1.22 GHCVER=7.10.3
+      compiler: ": #GHC 7.10.3"
+      addons: {apt: {packages: [cabal-install-1.22,ghc-7.10.3,hlint], sources: [hvr-ghc]}}
+    - env: CABALVER=1.24 GHCVER=8.0.1
+      compiler: ": #GHC 8.0.1"
+      addons: {apt: {packages: [cabal-install-1.24,ghc-8.0.1,hlint], sources: [hvr-ghc]}}
+    - env: CABALVER=1.24 GHCVER=head
+      compiler: ": #GHC head"
+      addons: {apt: {packages: [cabal-install-1.24,ghc-head,hlint], sources: [hvr-ghc]}}
+
+  allow_failures:
+    - env: CABALVER=1.24 GHCVER=head
+
 before_install:
-  # Uncomment whenever hackage is down.
-  # - mkdir -p ~/.cabal && cp travis/config ~/.cabal/config && cabal update
-  - travis/cabal-apt-install $mode
+ - unset CC
+ - export PATH=$HOME/.cabal/bin:/opt/ghc/$GHCVER/bin:/opt/cabal/$CABALVER/bin:$PATH
 
 install:
-  - cabal configure $mode
-  - cabal build
+ - cabal --version
+ - echo "$(ghc --version) [$(ghc --print-project-git-commit-id 2> /dev/null || echo '?')]"
+ - if [ -f $HOME/.cabal/packages/hackage.haskell.org/00-index.tar.gz ];
+   then
+     zcat $HOME/.cabal/packages/hackage.haskell.org/00-index.tar.gz >
+          $HOME/.cabal/packages/hackage.haskell.org/00-index.tar;
+   fi
+ - travis_retry cabal update -v
+ - sed -i 's/^jobs:/-- jobs:/' ${HOME}/.cabal/config
+ - cabal install --only-dependencies --enable-tests --dry -v > installplan.txt
+ - sed -i -e '1,/^Resolving /d' installplan.txt; cat installplan.txt
 
+# check whether current requested install-plan matches cached package-db snapshot
+ - if diff -u installplan.txt $HOME/.cabsnap/installplan.txt;
+   then
+     echo "cabal build-cache HIT";
+     rm -rfv .ghc;
+     cp -a $HOME/.cabsnap/ghc $HOME/.ghc;
+     cp -a $HOME/.cabsnap/lib $HOME/.cabsnap/share $HOME/.cabsnap/bin $HOME/.cabal/;
+   else
+     echo "cabal build-cache MISS";
+     rm -rf $HOME/.cabsnap;
+     mkdir -p $HOME/.ghc $HOME/.cabal/lib $HOME/.cabal/share $HOME/.cabal/bin;
+     cabal install -j --only-dependencies --enable-tests;
+     if [ "$GHCVER" = "7.10.3" ]; then cabal install Cabal-1.22.4.0; fi;
+   fi
+
+# snapshot package-db on cache miss
+ - if [ ! -d $HOME/.cabsnap ];
+   then
+      echo "snapshotting package-db to build-cache";
+      mkdir $HOME/.cabsnap;
+      cp -a $HOME/.ghc $HOME/.cabsnap/ghc;
+      cp -a $HOME/.cabal/lib $HOME/.cabal/share $HOME/.cabal/bin installplan.txt $HOME/.cabsnap/;
+   fi
+
+# Here starts the actual work to be performed for the package under
+# test; any command which exits with a non-zero exit code causes the
+# build to fail.
 script:
-  - $script && hlint src --cpp-define HLINT
+ # -v2 provides useful information for debugging
+ - cabal configure --enable-tests -v2
 
+ # this builds all libraries and executables
+ # (including tests/benchmarks)
+ - cabal build
+
+ - cabal test
+ - hlint src --cpp-define HLINT
+
+ # tests that a source-distribution can be generated
+ - cabal sdist
+
+ # check that the generated source-distribution can be built & installed
+ - export SRC_TGZ=$(cabal info . | awk '{print $2 ".tar.gz";exit}') ;
+   cd dist/;
+   if [ -f "$SRC_TGZ" ]; then
+      cabal install --force-reinstalls "$SRC_TGZ";
+   else
+      echo "expected '$SRC_TGZ' not found";
+      exit 1;
+   fi
+
 notifications:
   irc:
     channels:
@@ -19,5 +111,4 @@
     template:
       - "\x0313zippers\x03/\x0306%{branch}\x03 \x0314%{commit}\x03 %{build_url} %{message}"
 
-env:
-  - mode="--enable-tests" script="cabal test"
+# EOF
diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
--- a/CHANGELOG.markdown
+++ b/CHANGELOG.markdown
@@ -1,3 +1,7 @@
+0.2.1
+---
+* Migrate zipper benchmarks from lens
+
 0.1
 ---
 * Repository initialized
diff --git a/README.markdown b/README.markdown
--- a/README.markdown
+++ b/README.markdown
@@ -1,7 +1,7 @@
 zippers
 ===
 
-[![Build Status](https://secure.travis-ci.org/ekmett/zippers.png?branch=master)](http://travis-ci.org/ekmett/zippers)
+[![Hackage](https://img.shields.io/hackage/v/zippers.svg)](https://hackage.haskell.org/package/zippers) [![Build Status](https://secure.travis-ci.org/ekmett/zippers.png?branch=master)](http://travis-ci.org/ekmett/zippers)
 
 Zippers are a way of accessing and manipulating data deep within a structure. This library uses Lenses and Traversals from the lens library to do this effectively.
 
diff --git a/benchmarks/zipper.hs b/benchmarks/zipper.hs
new file mode 100644
--- /dev/null
+++ b/benchmarks/zipper.hs
@@ -0,0 +1,46 @@
+module Main
+       ( main -- :: IO ()
+       ) where
+
+import Control.Lens
+import Control.Zipper
+import Criterion.Main
+
+main :: IO ()
+main = defaultMain
+  [ bgroup "rezip"
+      [ bench "rezip"             $ nf tugAndRezip1 ['a'..'z']
+      , bench "farthest leftward" $ nf tugAndRezip2 ['a'..'z']
+      , bench "leftmost"          $ nf tugAndRezip3 ['a'..'z']
+      , bench "tugTo"             $ nf tugAndRezip4 ['a'..'z']
+      ]
+  , bgroup "zipper creation"
+      [ bench "over traverse id"  $ nf (over traverse id) ['a'..'z']
+      , bench "zipper"            $ nf zipTraverseRezip   ['a'..'z']
+      ]
+  , bgroup "downward"
+      [ bench "downward _1"       $ nf downwardAndRezip1 (['a'..'z'],['z'..'a'])
+      , bench "fromWithin"        $ nf downwardAndRezip2 (['a'..'z'],['z'..'a'])
+      ]
+  ]
+
+-- What's the fastest rezip of all?
+tugAndRezip1, tugAndRezip2, tugAndRezip3 :: String -> String
+tugAndRezip1 xs = zipntugs 25 xs & focus .~ 'a' & rezip
+tugAndRezip2 xs = zipntugs 25 xs & focus .~ 'b' & farthest leftward & rezip
+tugAndRezip3 xs = zipntugs 25 xs & focus .~ 'c' & leftmost & rezip
+tugAndRezip4 xs = zipntugs 25 xs & focus .~ 'd' & tugTo 0 & rezip
+
+zipntugs i x = zipper x & fromWithin traverse & tugs rightward i
+
+-- How fast is creating and destroying a zipper compared to
+-- a regular traversal?
+zipTraverseRezip x = zipper x & fromWithin traverse & rezip
+
+-- is 'downward' any faster than the composition of traverse?
+downwardAndRezip1 :: (String, String) -> (String, String)
+downwardAndRezip1 xs =
+  zipper xs & downward _1 & fromWithin traverse & focus .~ 'h' & rezip
+downwardAndRezip2 :: (String, String) -> (String, String)
+downwardAndRezip2 xs =
+  zipper xs & fromWithin (_1.traverse) & focus .~ 'g' & rezip
diff --git a/src/Control/Zipper/Internal.hs b/src/Control/Zipper/Internal.hs
--- a/src/Control/Zipper/Internal.hs
+++ b/src/Control/Zipper/Internal.hs
@@ -15,6 +15,10 @@
 {-# LANGUAGE Trustworthy #-}
 #endif
 
+#ifndef MIN_VERSION_base
+#define MIN_VERSION_base(x,y,z) 1
+#endif
+
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Control.Zipper.Internal
@@ -42,12 +46,15 @@
 import Control.Lens.Setter
 import Control.Lens.Traversal
 import Control.Lens.Type
-import Data.Foldable
 import Data.Functor.Apply
 import Data.Maybe
 import Data.Monoid
 import Data.Profunctor.Unsafe
 
+#if !(MIN_VERSION_base(4,8,0))
+import Data.Foldable
+#endif
+
 -- $setup
 -- >>> :set -XNoOverloadedStrings
 -- >>> import Control.Lens
@@ -406,7 +413,7 @@
 -- | Jerk the 'Zipper' one 'tooth' to the 'rightward' within the current 'Lens' or 'Traversal'.
 --
 -- Attempts to move past the start of the current 'Traversal' (or trivially, the current 'Lens')
--- will return 'Nothing'.
+-- will return 'mzero'.
 --
 -- >>> isNothing $ zipper "hello" & rightward
 -- True
@@ -420,13 +427,13 @@
 -- >>> rezip $ zipper (1,2) & fromWithin both & tug rightward & focus .~ 3
 -- (1,3)
 rightward :: MonadPlus m => h :> a:@i -> m (h :> a:@i)
-rightward (Zipper h t o p i a) = mover p (Leaf i a) mzero $ \q j b -> return $ Zipper h t (o + 1) q j b where
+rightward (Zipper h t o p i a) = mover p (Leaf i a) mzero $ \q j b -> return $ Zipper h t (o + 1) q j b
 {-# INLINE rightward #-}
 
 -- | Jerk the 'Zipper' 'leftward' one 'tooth' within the current 'Lens' or 'Traversal'.
 --
 -- Attempts to move past the end of the current 'Traversal' (or trivially, the current 'Lens')
--- will return 'Nothing'.
+-- will return 'mzero'.
 --
 -- >>> isNothing $ zipper "hello" & leftward
 -- True
@@ -560,7 +567,7 @@
 -- | Move the 'Zipper' horizontally to the element in the @n@th position in the
 -- current level, absolutely indexed, starting with the 'farthest' 'leftward' as @0@.
 --
--- This returns 'Nothing' if the target element doesn't exist.
+-- This returns 'mzero' if the target element doesn't exist.
 --
 -- @'jerkTo' n ≡ 'jerks' 'rightward' n '.' 'farthest' 'leftward'@
 --
diff --git a/zippers.cabal b/zippers.cabal
--- a/zippers.cabal
+++ b/zippers.cabal
@@ -1,6 +1,6 @@
 name:          zippers
 category:      zippers
-version:       0.2
+version:       0.2.1
 license:       BSD3
 cabal-version: >= 1.10
 license-file:  LICENSE
@@ -36,8 +36,8 @@
   build-depends:
     base >= 4.4 && < 5,
     lens >= 4 && < 5,
-    profunctors >= 4 && < 5,
-    semigroupoids >= 4 && < 5
+    profunctors >= 4 && < 6,
+    semigroupoids >= 4 && < 6
   exposed-modules:
     Control.Zipper
     Control.Zipper.Internal
@@ -52,6 +52,16 @@
     doctest >= 0.9.1,
     filepath
   ghc-options: -Wall -threaded
-  if impl(ghc<7.6.1)
-    ghc-options: -Werror
   hs-source-dirs: tests
+
+benchmark zipper
+  type:             exitcode-stdio-1.0
+  main-is:          zipper.hs
+  default-language: Haskell2010
+  ghc-options:      -O2 -threaded -fdicts-cheap -funbox-strict-fields
+  hs-source-dirs:   benchmarks
+  build-depends:
+    base,
+    criterion,
+    lens,
+    zippers