diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 52f03c57..5724f11b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -65,13 +65,7 @@ jobs:
     - run: |
         gem install bundler
         bundle install
-    - run: |
-        bundle exec mutant                                    \
-          --since HEAD~1                                      \
-          --zombie                                            \
-          --ignore-subject 'Unparser::CLI*'                   \
-          --ignore-subject 'Unparser::Validation.from_string' \
-          -- 'Unparser*'
+    - run: ./mutant.sh
   ruby-rubocop:
     name: Rubocop
     runs-on: ${{ matrix.os }}
diff --git a/Gemfile.lock b/Gemfile.lock
index 6c44554d..6adcf79b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    unparser (0.4.7)
+    unparser (0.4.8)
       abstract_type (~> 0.0.7)
       adamantium (~> 0.2.0)
       anima (~> 0.3.1)
diff --git a/README.md b/README.md
index 26c8d709..58053e24 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 unparser
 ========
 
-[![CI](https://github.com/mbj/unparser/workflows/CI/badge.svg)
+![CI](https://github.com/mbj/unparser/workflows/CI/badge.svg)
 [![Gem Version](https://img.shields.io/gem/v/unparser.svg)](https://rubygems.org/gems/unparser)
 
 Generate equivalent source for ASTs from whitequarks [parser](https://github.com/whitequark/parser).
diff --git a/mutant.sh b/mutant.sh
new file mode 100755
index 00000000..6014efbf
--- /dev/null
+++ b/mutant.sh
@@ -0,0 +1,8 @@
+#/usr/bin/bash -ex
+
+bundle exec mutant                                    \
+  --since HEAD~1                                      \
+  --zombie                                            \
+  --ignore-subject 'Unparser::CLI*'                   \
+  --ignore-subject 'Unparser::Validation.from_string' \
+  -- 'Unparser*'