diff --git a/.circleci/config.yml b/.circleci/config.yml
index 0ee8e73..8de098f 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -1,86 +1,16 @@
-# This configuration was automatically generated from a CircleCI 1.0 config.
-# It should include any build commands you had along with commands that CircleCI
-# inferred from your project structure. We strongly recommend you read all the
-# comments in this file to understand the structure of CircleCI 2.0, as the idiom
-# for configuration has changed substantially in 2.0 to allow arbitrary jobs rather
-# than the prescribed lifecycle of 1.0. In general, we recommend using this generated
-# configuration as a reference rather than using it in production, though in most
-# cases it should duplicate the execution of your original 1.0 config.
 version: 2
 jobs:
   build:
-    working_directory: ~/zsh-users/zsh-autosuggestions
     parallelism: 4
     shell: /bin/bash --login
-    # CircleCI 2.0 does not support environment variables that refer to each other the same way as 1.0 did.
-    # If any of these refer to each other, rewrite them so that they don't or see https://circleci.com/docs/2.0/env-vars/#interpolating-environment-variables-to-set-other-environment-variables .
-    environment:
-      CIRCLE_ARTIFACTS: /tmp/circleci-artifacts
-      CIRCLE_TEST_REPORTS: /tmp/circleci-test-results
-      ZSH_VERSIONS: zsh-dev/4.3.11 zsh/5.0.2 zsh/5.0.8 zsh/5.1.1 zsh/5.2 zsh/5.3.1 zsh/5.4.2 zsh/5.5.1
-    # In CircleCI 1.0 we used a pre-configured image with a large number of languages and other packages.
-    # In CircleCI 2.0 you can now specify your own image, or use one of our pre-configured images.
-    # The following configuration line tells CircleCI to use the specified docker image as the runtime environment for you job.
-    # We have selected a pre-built image that mirrors the build environment we use on
-    # the 1.0 platform, but we recommend you choose an image more tailored to the needs
-    # of each job. For more information on choosing an image (or alternatively using a
-    # VM instead of a container) see https://circleci.com/docs/2.0/executor-types/
-    # To see the list of pre-built images that CircleCI provides for most common languages see
-    # https://circleci.com/docs/2.0/circleci-images/
     docker:
-    - image: circleci/build-image:ubuntu-14.04-XXL-upstart-1189-5614f37
+    - image: ericfreese/zsh-autosuggestions-test:latest
       command: /sbin/init
     steps:
-    # Machine Setup
-    #   If you break your build into multiple jobs with workflows, you will probably want to do the parts of this that are relevant in each
-    # The following `checkout` command checks out your code to your working directory. In 1.0 we did this implicitly. In 2.0 you can choose where in the course of a job your code should be checked out.
     - checkout
-    # Prepare for artifact and test results  collection equivalent to how it was done on 1.0.
-    # In many cases you can simplify this from what is generated here.
-    # 'See docs on artifact collection here https://circleci.com/docs/2.0/artifacts/'
-    - run: mkdir -p $CIRCLE_ARTIFACTS $CIRCLE_TEST_REPORTS
-    # Dependencies
-    #   This would typically go in either a build or a build-and-test job when using workflows
-    # Restore the dependency cache
-    - restore_cache:
-        keys:
-        # This branch if available
-        - v1-dep-{{ .Branch }}-
-        # Default branch if not
-        - v1-dep-master-
-        # Any branch if there are none on the default branch - this should be unnecessary if you have your default branch configured correctly
-        - v1-dep-
-    # This is based on your 1.0 configuration file or project settings
-    - run: for v in $(echo $ZSH_VERSIONS | awk "{ for (i=$((1+CIRCLE_NODE_INDEX));i<=NF;i+=$CIRCLE_NODE_TOTAL) print \$i }"); do wget https://sourceforge.net/projects/zsh/files/$v/zsh-${v#*/}.tar.gz && tar xzf zsh-${v#*/}.tar.gz && pushd zsh-${v#*/} && ./configure && sudo make install && popd || exit 1; done
-    # The following line was run implicitly in your 1.0 builds based on what CircleCI inferred about the structure of your project. In 2.0 you need to be explicit about which commands should be run. In some cases you can discard inferred commands if they are not relevant to your project.
-    - run: echo -e "export RAILS_ENV=test\nexport RACK_ENV=test" >> $BASH_ENV
-    - run: 'bundle check --path=vendor/bundle || bundle install --path=vendor/bundle
-        --jobs=4 --retry=3 '
-    # Save dependency cache
-    - save_cache:
-        key: v1-dep-{{ .Branch }}-{{ epoch }}
-        paths:
-        # This is a broad list of cache paths to include many possible development environments
-        # You can probably delete some of these entries
-        - vendor/bundle
-        - ~/virtualenvs
-        - ~/.m2
-        - ~/.ivy2
-        - ~/.bundle
-        - ~/.go_workspace
-        - ~/.gradle
-        - ~/.cache/bower
-    # Test
-    #   This would typically be a build job when using workflows, possibly combined with build
-    # This is based on your 1.0 configuration file or project settings
-    - run: for v in $(echo $ZSH_VERSIONS | awk "{ for (i=$((1+CIRCLE_NODE_INDEX));i<=NF;i+=$CIRCLE_NODE_TOTAL) print \$i }"); do TEST_ZSH_BIN=/usr/local/bin/zsh-${v#*/} make test || exit 1; done
-    # Teardown
-    #   If you break your build into multiple jobs with workflows, you will probably want to do the parts of this that are relevant in each
-    # Save test results
-    - store_test_results:
-        path: /tmp/circleci-test-results
-    # Save artifacts
-    - store_artifacts:
-        path: /tmp/circleci-artifacts
-    - store_artifacts:
-        path: /tmp/circleci-test-results
+    - run:
+        name: Running tests
+        command: |
+          for v in $(grep "^[^#]" ZSH_VERSIONS | awk "(NR + $CIRCLE_NODE_INDEX) % $CIRCLE_NODE_TOTAL == 0"); do
+            TEST_ZSH_BIN=zsh-$v make test || exit 1
+          done
diff --git a/.ruby-version b/.ruby-version
index 2bf1c1c..aedc15b 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-2.3.1
+2.5.3
diff --git a/Dockerfile b/Dockerfile
new file mode 100644
index 0000000..0d51407
--- /dev/null
+++ b/Dockerfile
@@ -0,0 +1,20 @@
+FROM ruby:2.5.3-alpine
+
+RUN apk add --no-cache autoconf
+RUN apk add --no-cache libtool
+RUN apk add --no-cache libcap-dev
+RUN apk add --no-cache pcre-dev
+RUN apk add --no-cache curl
+RUN apk add --no-cache build-base
+RUN apk add --no-cache ncurses-dev
+RUN apk add --no-cache tmux
+
+WORKDIR /zsh-autosuggestions
+
+ADD ZSH_VERSIONS /zsh-autosuggestions/ZSH_VERSIONS
+ADD install_test_zsh.sh /zsh-autosuggestions/install_test_zsh.sh
+RUN ./install_test_zsh.sh
+
+ADD Gemfile /zsh-autosuggestions/Gemfile
+ADD Gemfile.lock /zsh-autosuggestions/Gemfile.lock
+RUN bundle install
diff --git a/README.md b/README.md
index 65274e8..59ee831 100644
--- a/README.md
+++ b/README.md
@@ -142,6 +142,20 @@ Tests are written in ruby using the [`rspec`](http://rspec.info/) framework. The
 
 Test files live in `spec/`. To run the tests, run `make test`. To run a specific test, run `TESTS=spec/some_spec.rb make test`. You can also specify a `zsh` binary to use by setting the `TEST_ZSH_BIN` environment variable (ex: `TEST_ZSH_BIN=/bin/zsh make test`).
 
+A docker image for testing is available [on docker hub](https://hub.docker.com/r/ericfreese/zsh-autosuggestions-test). It comes with ruby, the bundler dependencies, and all supported versions of zsh installed.
+
+Pull the docker image with:
+
+```sh
+docker pull ericfreese/zsh-autosuggestions-test
+```
+
+To run the tests for a specific version of zsh (where `<version>` below is substituted with the contents of a line from the [`ZSH_VERSIONS`](ZSH_VERSIONS) file):
+
+```sh
+docker run -it -e TEST_ZSH_BIN=zsh-<version> -v $PWD:/zsh-autosuggestions zsh-autosuggestions-test make test
+```
+
 
 ## License
 
diff --git a/ZSH_VERSIONS b/ZSH_VERSIONS
new file mode 100644
index 0000000..e08b87c
--- /dev/null
+++ b/ZSH_VERSIONS
@@ -0,0 +1,15 @@
+# Zsh releases to run tests against
+# See https://github.com/zsh-users/zsh/releases
+#
+# When modifying this file, rebuild and push docker image:
+#   $ docker build -t ericfreese/zsh-autosuggestions-test .
+#   $ docker push ericfreese/zsh-autosuggestions-test
+4.3.11
+5.0.2
+5.0.8
+5.1.1
+5.2
+5.3.1
+5.4.2
+5.5.1
+5.6.2
diff --git a/circle.yml b/circle.yml
deleted file mode 100644
index c804ae1..0000000
--- a/circle.yml
+++ /dev/null
@@ -1,12 +0,0 @@
-machine:
-  environment:
-    ZSH_VERSIONS: zsh-dev/4.3.11 zsh/5.0.2 zsh/5.0.8 zsh/5.1.1 zsh/5.2 zsh/5.3.1 zsh/5.4.2 zsh/5.5.1
-
-dependencies:
-  pre:
-    - for v in $(echo $ZSH_VERSIONS | awk "{ for (i=$((1+CIRCLE_NODE_INDEX));i<=NF;i+=$CIRCLE_NODE_TOTAL) print \$i }"); do wget https://sourceforge.net/projects/zsh/files/$v/zsh-${v#*/}.tar.gz && tar xzf zsh-${v#*/}.tar.gz && pushd zsh-${v#*/} && ./configure && sudo make install && popd || exit 1; done
-
-test:
-  override:
-    - for v in $(echo $ZSH_VERSIONS | awk "{ for (i=$((1+CIRCLE_NODE_INDEX));i<=NF;i+=$CIRCLE_NODE_TOTAL) print \$i }"); do TEST_ZSH_BIN=/usr/local/bin/zsh-${v#*/} make test || exit 1; done:
-        parallel: true
diff --git a/install_test_zsh.sh b/install_test_zsh.sh
new file mode 100755
index 0000000..1578183
--- /dev/null
+++ b/install_test_zsh.sh
@@ -0,0 +1,26 @@
+#!/bin/sh
+
+set -ex
+
+for v in $(grep "^[^#]" ZSH_VERSIONS); do
+  mkdir zsh-$v
+  cd zsh-$v
+
+  curl -L https://api.github.com/repos/zsh-users/zsh/tarball/zsh-$v | tar xz --strip=1
+
+  ./Util/preconfig
+  ./configure --enable-pcre \
+              --enable-cap \
+              --enable-multibyte \
+              --with-term-lib='ncursesw tinfo' \
+              --without-tcsetpgrp \
+              --program-suffix="-$v"
+
+  make install.bin
+  make install.modules
+  make install.fns
+
+  cd ..
+
+  rm -rf zsh-$v
+done