diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
--- a/.travis.yml
+++ /dev/null
@@ -1,179 +0,0 @@
-# This Travis job script has been generated by a script via
-#
-#   haskell-ci '--output=.travis.yml' '--config=cabal.haskell-ci' 'cabal.project'
-#
-# For more information, see https://github.com/haskell-CI/haskell-ci
-#
-# version: 0.5.20180830
-#
-language: c
-dist: xenial
-git:
-  # whether to recursively clone submodules
-  submodules: false
-notifications:
-  irc:
-    channels:
-      - irc.freenode.org#haskell-lens
-    skip_join: true
-    template:
-      - "\"\\x0313intervals\\x03/\\x0306%{branch}\\x03 \\x0314%{commit}\\x03 %{build_url} %{message}\""
-cache:
-  directories:
-    - $HOME/.cabal/packages
-    - $HOME/.cabal/store
-before_cache:
-  - rm -fv $CABALHOME/packages/hackage.haskell.org/build-reports.log
-  # remove files that are regenerated by 'cabal update'
-  - rm -fv $CABALHOME/packages/hackage.haskell.org/00-index.*
-  - rm -fv $CABALHOME/packages/hackage.haskell.org/*.json
-  - rm -fv $CABALHOME/packages/hackage.haskell.org/01-index.cache
-  - rm -fv $CABALHOME/packages/hackage.haskell.org/01-index.tar
-  - rm -fv $CABALHOME/packages/hackage.haskell.org/01-index.tar.idx
-  - rm -rfv $CABALHOME/packages/head.hackage
-matrix:
-  include:
-    - compiler: ghc-8.8.1
-      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-8.8.1","cabal-install-3.0"]}}
-    - compiler: ghc-8.6.5
-      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-8.6.5","cabal-install-3.0"]}}
-    - compiler: ghc-8.4.4
-      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-8.4.4","cabal-install-3.0"]}}
-    - compiler: ghc-8.2.2
-      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-8.2.2","cabal-install-3.0"]}}
-    - compiler: ghc-8.0.2
-      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-8.0.2","cabal-install-3.0"]}}
-    - compiler: ghc-7.10.3
-      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-7.10.3","cabal-install-3.0"]}}
-    - compiler: ghc-7.8.4
-      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-7.8.4","cabal-install-3.0"]}}
-    - compiler: ghc-7.6.3
-      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-7.6.3","cabal-install-3.0"]}}
-    - compiler: ghc-7.4.2
-      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-7.4.2","cabal-install-3.0"]}}
-    - compiler: ghc-7.2.2
-      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-7.2.2","cabal-install-3.0"]}}
-    - compiler: ghc-7.0.4
-      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-7.0.4","cabal-install-3.0"]}}
-    - compiler: ghc-head
-      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-head","cabal-install-head"]}}
-  allow_failures:
-    - compiler: ghc-head
-    - compiler: ghc-7.0.4
-    - compiler: ghc-7.2.2
-before_install:
-  - HC=$(echo "/opt/$CC/bin/ghc" | sed 's/-/\//')
-  - WITHCOMPILER="-w $HC"
-  - HADDOCK=$(echo "/opt/$CC/bin/haddock" | sed 's/-/\//')
-  - HCPKG="$HC-pkg"
-  - unset CC
-  - CABAL=/opt/ghc/bin/cabal
-  - CABALHOME=$HOME/.cabal
-  - export PATH="$CABALHOME/bin:$PATH"
-  - TOP=$(pwd)
-  - "HCNUMVER=$(${HC} --numeric-version|perl -ne '/^(\\d+)\\.(\\d+)\\.(\\d+)(\\.(\\d+))?$/; print(10000 * $1 + 100 * $2 + ($3 == 0 ? $5 != 1 : $3))')"
-  - echo $HCNUMVER
-  - CABAL="$CABAL -vnormal+nowrap+markoutput"
-  - set -o pipefail
-  - |
-    echo 'function blue(s) { printf "\033[0;34m" s "\033[0m " }'           >> .colorful.awk
-    echo 'BEGIN { state = "output"; }'                                     >> .colorful.awk
-    echo '/^-----BEGIN CABAL OUTPUT-----$/ { state = "cabal" }'            >> .colorful.awk
-    echo '/^-----END CABAL OUTPUT-----$/ { state = "output" }'             >> .colorful.awk
-    echo '!/^(-----BEGIN CABAL OUTPUT-----|-----END CABAL OUTPUT-----)/ {' >> .colorful.awk
-    echo '  if (state == "cabal") {'                                       >> .colorful.awk
-    echo '    print blue($0)'                                              >> .colorful.awk
-    echo '  } else {'                                                      >> .colorful.awk
-    echo '    print $0'                                                    >> .colorful.awk
-    echo '  }'                                                             >> .colorful.awk
-    echo '}'                                                               >> .colorful.awk
-  - cat .colorful.awk
-  - |
-    color_cabal_output () {
-      awk -f $TOP/.colorful.awk
-    }
-  - echo text | color_cabal_output
-install:
-  - ${CABAL} --version
-  - echo "$(${HC} --version) [$(${HC} --print-project-git-commit-id 2> /dev/null || echo '?')]"
-  - TEST=--enable-tests
-  - if [ $HCNUMVER -lt 70600 ] ; then TEST=--disable-tests ; fi
-  - BENCH=--enable-benchmarks
-  - HEADHACKAGE=false
-  - if [ $HCNUMVER -gt 80801 ] ; then HEADHACKAGE=true ; fi
-  - rm -f $CABALHOME/config
-  - |
-    echo "verbose: normal +nowrap +markoutput"          >> $CABALHOME/config
-    echo "remote-build-reporting: anonymous"            >> $CABALHOME/config
-    echo "write-ghc-environment-files: always"          >> $CABALHOME/config
-    echo "remote-repo-cache: $CABALHOME/packages"       >> $CABALHOME/config
-    echo "logs-dir:          $CABALHOME/logs"           >> $CABALHOME/config
-    echo "world-file:        $CABALHOME/world"          >> $CABALHOME/config
-    echo "extra-prog-path:   $CABALHOME/bin"            >> $CABALHOME/config
-    echo "symlink-bindir:    $CABALHOME/bin"            >> $CABALHOME/config
-    echo "installdir:        $CABALHOME/bin"            >> $CABALHOME/config
-    echo "build-summary:     $CABALHOME/logs/build.log" >> $CABALHOME/config
-    echo "store-dir:         $CABALHOME/store"          >> $CABALHOME/config
-    echo "install-dirs user"                            >> $CABALHOME/config
-    echo "  prefix: $CABALHOME"                         >> $CABALHOME/config
-    echo "repository hackage.haskell.org"               >> $CABALHOME/config
-    echo "  url: http://hackage.haskell.org/"           >> $CABALHOME/config
-  - |
-    if $HEADHACKAGE; then
-    echo "allow-newer: $($HCPKG list --simple-output | sed -E 's/([a-zA-Z-]+)-[0-9.]+/*:\1/g')" >> $CABALHOME/config
-    echo "repository head.hackage.ghc.haskell.org"                                        >> $CABALHOME/config
-    echo "   url: https://ghc.gitlab.haskell.org/head.hackage/"                           >> $CABALHOME/config
-    echo "   secure: True"                                                                >> $CABALHOME/config
-    echo "   root-keys: 7541f32a4ccca4f97aea3b22f5e593ba2c0267546016b992dfadcd2fe944e55d" >> $CABALHOME/config
-    echo "              26021a13b401500c8eb2761ca95c61f2d625bfef951b939a8124ed12ecf07329" >> $CABALHOME/config
-    echo "              f76d08be13e9a61a377a85e2fb63f4c5435d40f8feb3e12eb05905edb8cdea89" >> $CABALHOME/config
-    echo "   key-threshold: 3"                                                            >> $CABALHOME/config
-    fi
-  - cat $CABALHOME/config
-  - rm -fv cabal.project cabal.project.local cabal.project.freeze
-  - travis_retry ${CABAL} v2-update -v
-  # Generate cabal.project
-  - rm -rf cabal.project cabal.project.local cabal.project.freeze
-  - touch cabal.project
-  - |
-    echo "packages: ." >> cabal.project
-  - |
-  - "for pkg in $($HCPKG list --simple-output); do echo $pkg | sed 's/-[^-]*$//' | (grep -vE -- '^(intervals)$' || true) | sed 's/^/constraints: /' | sed 's/$/ installed/' >> cabal.project.local; done"
-  - cat cabal.project || true
-  - cat cabal.project.local || true
-  - if [ -f "./configure.ac" ]; then (cd "." && autoreconf -i); fi
-  - ${CABAL} v2-freeze $WITHCOMPILER ${TEST} ${BENCH} | color_cabal_output
-  - "cat cabal.project.freeze | sed -E 's/^(constraints: *| *)//' | sed 's/any.//'"
-  - rm  cabal.project.freeze
-  - ${CABAL} v2-build $WITHCOMPILER ${TEST} ${BENCH} --dep -j2 all | color_cabal_output
-script:
-  - DISTDIR=$(mktemp -d /tmp/dist-test.XXXX)
-  # Packaging...
-  - ${CABAL} v2-sdist all | color_cabal_output
-  # Unpacking...
-  - mv dist-newstyle/sdist/*.tar.gz ${DISTDIR}/
-  - cd ${DISTDIR} || false
-  - find . -maxdepth 1 -type f -name '*.tar.gz' -exec tar -xvf '{}' \;
-  - find . -maxdepth 1 -type f -name '*.tar.gz' -exec rm       '{}' \;
-  - PKGDIR_intervals="$(find . -maxdepth 1 -type d -regex '.*/intervals-[0-9.]*')"
-  # Generate cabal.project
-  - rm -rf cabal.project cabal.project.local cabal.project.freeze
-  - touch cabal.project
-  - |
-    echo "packages: ${PKGDIR_intervals}" >> cabal.project
-  - |
-  - "for pkg in $($HCPKG list --simple-output); do echo $pkg | sed 's/-[^-]*$//' | (grep -vE -- '^(intervals)$' || true) | sed 's/^/constraints: /' | sed 's/$/ installed/' >> cabal.project.local; done"
-  - cat cabal.project || true
-  - cat cabal.project.local || true
-  # Building with tests and benchmarks...
-  # build & run tests, build benchmarks
-  - ${CABAL} v2-build $WITHCOMPILER ${TEST} ${BENCH} all | color_cabal_output
-  # Testing...
-  - if [ $HCNUMVER -ge 70600 ] ; then ${CABAL} v2-test $WITHCOMPILER ${TEST} ${BENCH} all | color_cabal_output ; fi
-  # cabal check...
-  - (cd ${PKGDIR_intervals} && ${CABAL} -vnormal check)
-  # haddock...
-  - ${CABAL} v2-haddock $WITHCOMPILER --with-haddock $HADDOCK ${TEST} ${BENCH} all | color_cabal_output
-
-# REGENDATA ["--output=.travis.yml","--config=cabal.haskell-ci","cabal.project"]
-# EOF
diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
--- a/CHANGELOG.markdown
+++ b/CHANGELOG.markdown
@@ -1,3 +1,11 @@
+0.9.2 [2021.02.17]
+------------------
+* Export `(/=!)` and `(/=?)` operators.
+* The build-type has been changed from `Custom` to `Simple`.
+  To achieve this, the `doctests` test suite has been removed in favor of using
+  [`cabal-docspec`](https://github.com/phadej/cabal-extras/tree/master/cabal-docspec)
+  to run the doctests.
+
 0.9.1 [2020.01.29]
 ------------------
 * Add `Semigroup` instances for the `Interval` types in `Numeric.Interval`,
diff --git a/README.markdown b/README.markdown
--- a/README.markdown
+++ b/README.markdown
@@ -1,7 +1,7 @@
 intervals
 ==========
 
-[![Hackage](https://img.shields.io/hackage/v/intervals.svg)](https://hackage.haskell.org/package/intervals) [![Build Status](https://secure.travis-ci.org/ekmett/intervals.svg?branch=master)](http://travis-ci.org/ekmett/intervals)
+[![Hackage](https://img.shields.io/hackage/v/intervals.svg)](https://hackage.haskell.org/package/intervals) [![Build Status](https://github.com/ekmett/intervals/workflows/Haskell-CI/badge.svg)](https://github.com/ekmett/intervals/actions?query=workflow%3AHaskell-CI)
 
 Basic interval arithmetic
 
diff --git a/Setup.lhs b/Setup.lhs
--- a/Setup.lhs
+++ b/Setup.lhs
@@ -1,34 +1,7 @@
-\begin{code}
-{-# LANGUAGE CPP #-}
-{-# OPTIONS_GHC -Wall #-}
-module Main (main) where
-
-#ifndef MIN_VERSION_cabal_doctest
-#define MIN_VERSION_cabal_doctest(x,y,z) 0
-#endif
-
-#if MIN_VERSION_cabal_doctest(1,0,0)
-
-import Distribution.Extra.Doctest ( defaultMainWithDoctests )
-main :: IO ()
-main = defaultMainWithDoctests "doctests"
-
-#else
-
-#ifdef MIN_VERSION_Cabal
--- If the macro is defined, we have new cabal-install,
--- but for some reason we don't have cabal-doctest in package-db
---
--- Probably we are running cabal sdist, when otherwise using new-build
--- workflow
-import Warning ()
-#endif
-
-import Distribution.Simple
-
-main :: IO ()
-main = defaultMain
+#!/usr/bin/runhaskell
+> module Main (main) where
 
-#endif
+> import Distribution.Simple
 
-\end{code}
+> main :: IO ()
+> main = defaultMain
diff --git a/Warning.hs b/Warning.hs
deleted file mode 100644
--- a/Warning.hs
+++ /dev/null
@@ -1,5 +0,0 @@
-module Warning
-  {-# WARNING ["You are configuring this package without cabal-doctest installed.",
-               "The doctests test-suite will not work as a result.",
-               "To fix this, install cabal-doctest before configuring."] #-}
-  () where
diff --git a/intervals.cabal b/intervals.cabal
--- a/intervals.cabal
+++ b/intervals.cabal
@@ -1,5 +1,5 @@
 name:              intervals
-version:           0.9.1
+version:           0.9.2
 synopsis:          Interval Arithmetic
 description:
   A 'Numeric.Interval.Interval' is a closed, convex set of floating point values.
@@ -15,8 +15,8 @@
 author:             Edward Kmett
 maintainer:         ekmett@gmail.com
 category:           Math
-build-type:         Custom
-cabal-version:      >=1.8
+build-type:         Simple
+cabal-version:      >=1.10
 tested-with:        GHC == 7.0.4
                   , GHC == 7.2.2
                   , GHC == 7.4.2
@@ -27,31 +27,17 @@
                   , GHC == 8.2.2
                   , GHC == 8.4.4
                   , GHC == 8.6.5
-                  , GHC == 8.8.1
+                  , GHC == 8.8.3
+                  , GHC == 8.10.1
 extra-source-files:
   .hlint.yaml
-  .travis.yml
   CHANGELOG.markdown
   README.markdown
-  Warning.hs
 
 source-repository head
   type: git
   location: git://github.com/ekmett/intervals.git
 
-custom-setup
-  setup-depends:
-    base >= 4 && <5,
-    Cabal,
-    cabal-doctest >= 1 && <1.1
-
--- You can disable the doctests test suite with -f-test-doctests
-flag test-doctests
-  description: Enable (or disable via f-test-doctests) the doctest suite when
-               using the enable-tests option for cabal.
-  default: True
-  manual: True
-
 flag herbie
   default: False
   manual: True
@@ -85,21 +71,14 @@
     cpp-options: -DHERBIE
     ghc-options: -fplugin=Herbie
 
+  default-language: Haskell2010
+  x-docspec-options: --check-properties
+  x-docspec-property-variables: i x y xs ys
 
 test-suite doctests
   type:           exitcode-stdio-1.0
   main-is:        doctests.hs
   ghc-options:    -Wall -threaded
   hs-source-dirs: tests
-
-  if !flag(test-doctests) || !impl(ghc >= 7.6)
-    buildable: False
-  else
-    build-depends:
-      base           >= 4.6,
-      directory      >= 1.0,
-      doctest        >= 0.11.1 && < 0.17,
-      filepath,
-      intervals,
-      QuickCheck,
-      template-haskell
+  build-depends:  base, QuickCheck >=2.14.2
+  default-language: Haskell2010
diff --git a/src/Numeric/Interval.hs b/src/Numeric/Interval.hs
--- a/src/Numeric/Interval.hs
+++ b/src/Numeric/Interval.hs
@@ -38,8 +38,8 @@
   , scale, symmetric
   , contains
   , isSubsetOf
-  , certainly, (<!), (<=!), (==!), (>=!), (>!)
-  , possibly, (<?), (<=?), (==?), (>=?), (>?)
+  , certainly, (<!), (<=!), (==!), (/=!), (>=!), (>!)
+  , possibly, (<?), (<=?), (==?), (/=?), (>=?), (>?)
   , idouble
   , ifloat
   , iquot
diff --git a/src/Numeric/Interval/Internal.hs b/src/Numeric/Interval/Internal.hs
--- a/src/Numeric/Interval/Internal.hs
+++ b/src/Numeric/Interval/Internal.hs
@@ -46,8 +46,8 @@
   , scale, symmetric
   , contains
   , isSubsetOf
-  , certainly, (<!), (<=!), (==!), (>=!), (>!)
-  , possibly, (<?), (<=?), (==?), (>=?), (>?)
+  , certainly, (<!), (<=!), (==!), (/=!), (>=!), (>!)
+  , possibly, (<?), (<=?), (==?), (/=?), (>=?), (>?)
   , idouble
   , ifloat
   , iquot
@@ -69,6 +69,11 @@
 import qualified Data.Monoid
 
 -- $setup
+-- -- Eta expansion needed for GHC-7.6
+-- >>> :set -fno-warn-deprecations
+-- >>> let null xs = Numeric.Interval.Internal.null xs
+-- >>> let elem x xs = Numeric.Interval.Internal.elem x xs
+-- >>> let notElem x xs = Numeric.Interval.Internal.notElem x xs
 
 data Interval a = I !a !a | Empty deriving
   ( Eq, Ord
diff --git a/src/Numeric/Interval/Kaucher.hs b/src/Numeric/Interval/Kaucher.hs
--- a/src/Numeric/Interval/Kaucher.hs
+++ b/src/Numeric/Interval/Kaucher.hs
@@ -44,8 +44,8 @@
   , scale, symmetric
   , contains
   , isSubsetOf
-  , certainly, (<!), (<=!), (==!), (>=!), (>!)
-  , possibly, (<?), (<=?), (==?), (>=?), (>?)
+  , certainly, (<!), (<=!), (==!), (/=!), (>=!), (>!)
+  , possibly, (<?), (<=?), (==?), (/=?), (>=?), (>?)
   , clamp
   , idouble
   , ifloat
@@ -76,6 +76,11 @@
 import qualified Data.Monoid
 
 -- $setup
+-- -- Eta expansion needed for GHC-7.6
+-- >>> :set -fno-warn-deprecations
+-- >>> let null xs = Numeric.Interval.Kaucher.null xs
+-- >>> let elem x xs = Numeric.Interval.Kaucher.elem x xs
+-- >>> let notElem x xs = Numeric.Interval.Kaucher.notElem x xs
 
 data Interval a = I !a !a deriving
   ( Eq, Ord
diff --git a/src/Numeric/Interval/NonEmpty.hs b/src/Numeric/Interval/NonEmpty.hs
--- a/src/Numeric/Interval/NonEmpty.hs
+++ b/src/Numeric/Interval/NonEmpty.hs
@@ -41,8 +41,8 @@
   , mignitude
   , contains
   , isSubsetOf
-  , certainly, (<!), (<=!), (==!), (>=!), (>!)
-  , possibly, (<?), (<=?), (==?), (>=?), (>?)
+  , certainly, (<!), (<=!), (==!), (/=!), (>=!), (>!)
+  , possibly, (<?), (<=?), (==?), (/=?), (>=?), (>?)
   , clamp
   , inflate, deflate
   , scale, symmetric
diff --git a/src/Numeric/Interval/NonEmpty/Internal.hs b/src/Numeric/Interval/NonEmpty/Internal.hs
--- a/src/Numeric/Interval/NonEmpty/Internal.hs
+++ b/src/Numeric/Interval/NonEmpty/Internal.hs
@@ -40,8 +40,8 @@
   , mignitude
   , contains
   , isSubsetOf
-  , certainly, (<!), (<=!), (==!), (>=!), (>!)
-  , possibly, (<?), (<=?), (==?), (>=?), (>?)
+  , certainly, (<!), (<=!), (==!), (/=!), (>=!), (>!)
+  , possibly, (<?), (<=?), (==?), (/=?), (>=?), (>?)
   , clamp
   , inflate, deflate
   , scale, symmetric
@@ -67,6 +67,7 @@
 -- >>> import Test.QuickCheck.Gen hiding (scale)
 -- >>> import Test.QuickCheck.Property
 -- >>> import Control.Applicative
+-- >>> import Control.Exception
 -- >>> :set -XNoMonomorphismRestriction
 -- >>> :set -XExtendedDefaultRules
 -- >>> default (Integer,Double)
@@ -77,6 +78,11 @@
 -- >>> let conservativeExceptNaN sf f xs = forAll (choose (inf xs, sup xs)) $ \x -> isNaN (sf x) || (sf x) `member` (f xs)
 -- >>> let compose2 = fmap . fmap
 -- >>> let commutative op a b = (a `op` b) == (b `op` a)
+--
+-- -- Eta expansion needed for GHC-7.6
+-- >>> :set -fno-warn-deprecations
+-- >>> let elem x xs = Numeric.Interval.NonEmpty.Internal.elem x xs
+-- >>> let notElem x xs = Numeric.Interval.NonEmpty.Internal.notElem x xs
 
 data Interval a = I !a !a deriving
   ( Eq, Ord
@@ -491,7 +497,7 @@
   cos = periodic (2 * pi) (symmetric 1) (signum' . negate . sin) cos
   tan = periodic pi       whole         (const GT)               tan -- derivative only has to have correct sign
   asin (I a b) = (asin' a) ... (asin' b)
-    where 
+    where
       asin' x | x >= 1 = halfPi
               | x <= -1 = -halfPi
               | otherwise = asin x
diff --git a/tests/doctests.hs b/tests/doctests.hs
--- a/tests/doctests.hs
+++ b/tests/doctests.hs
@@ -7,19 +7,13 @@
 -- Stability   :  provisional
 -- Portability :  portable
 --
--- This module provides doctests for a project based on the actual versions
--- of the packages it was built with. It requires a corresponding Setup.lhs
--- to be added to the project
+-- This module exists to add dependencies
 -----------------------------------------------------------------------------
 module Main where
 
-import Build_doctests (flags, pkgs, module_sources)
-import Data.Foldable (traverse_)
-import Test.DocTest
-
 main :: IO ()
 main = do
-    traverse_ putStrLn args
-    doctest args
-  where
-    args = flags ++ pkgs ++ module_sources
+    putStrLn "This test-suite exists only to add dependencies"
+    putStrLn "To run doctests: "
+    putStrLn "    cabal build all --enable-tests"
+    putStrLn "    cabal-docspec"