diff --git a/test/.eslintrc.yaml b/test/.eslintrc.yaml
deleted file mode 100644
index add5a78..0000000
--- a/test/.eslintrc.yaml
+++ /dev/null
@@ -1,2 +0,0 @@
-parserOptions:
-  sourceType: module
diff --git a/test/base.js b/test/base.js
index 1bef3e3..32eff27 100644
--- a/test/base.js
+++ b/test/base.js
@@ -1,3 +1,4 @@
+'use strict'
 const test = require('ava')
 const path = require('path')
 
diff --git a/test/cli.js b/test/cli.js
index d2e449c..0cdc7dc 100644
--- a/test/cli.js
+++ b/test/cli.js
@@ -1,3 +1,4 @@
+'use strict'
 const test = require('ava')
 
 const cli = require('./helpers/cli.js')
diff --git a/test/config.js b/test/config.js
index 774e2f5..b8b3de5 100644
--- a/test/config.js
+++ b/test/config.js
@@ -1,3 +1,4 @@
+'use strict'
 const test = require('ava')
 const path = require('path')
 
diff --git a/test/dir.js b/test/dir.js
index 51c0b6e..ec4e60e 100644
--- a/test/dir.js
+++ b/test/dir.js
@@ -1,3 +1,4 @@
+'use strict'
 const test = require('ava')
 const path = require('path')
 
diff --git a/test/error.js b/test/error.js
index e53ce05..4dace3c 100644
--- a/test/error.js
+++ b/test/error.js
@@ -1,3 +1,4 @@
+'use strict'
 const test = require('ava')
 
 const tmp = require('./helpers/tmp.js')
diff --git a/test/ext.js b/test/ext.js
index 3f6e883..7016782 100644
--- a/test/ext.js
+++ b/test/ext.js
@@ -1,3 +1,4 @@
+'use strict'
 const test = require('ava')
 
 const fs = require('fs-extra')
diff --git a/test/fixtures/_bad-plugin.js b/test/fixtures/_bad-plugin.js
index 2911e95..7a4ffeb 100644
--- a/test/fixtures/_bad-plugin.js
+++ b/test/fixtures/_bad-plugin.js
@@ -1 +1,2 @@
+'use strict'
 throw new Error('This fails')
diff --git a/test/glob.js b/test/glob.js
index 574cebb..e60b75a 100644
--- a/test/glob.js
+++ b/test/glob.js
@@ -1,3 +1,4 @@
+'use strict'
 const test = require('ava')
 const path = require('path')
 
diff --git a/test/helpers/clean.js b/test/helpers/clean.js
index 526bedf..cabfc72 100644
--- a/test/helpers/clean.js
+++ b/test/helpers/clean.js
@@ -1,4 +1,4 @@
-'use strict' // eslint-disable-line
+'use strict'
 const fs = require('fs-extra')
 
 Promise.all([
diff --git a/test/helpers/cli.js b/test/helpers/cli.js
index 7512439..64b9154 100644
--- a/test/helpers/cli.js
+++ b/test/helpers/cli.js
@@ -1,3 +1,4 @@
+'use strict'
 const path = require('path')
 const { exec } = require('child_process')
 
diff --git a/test/helpers/env.js b/test/helpers/env.js
index 2fad200..b389370 100644
--- a/test/helpers/env.js
+++ b/test/helpers/env.js
@@ -1,3 +1,4 @@
+'use strict'
 const fs = require('fs-extra')
 const path = require('path')
 const globby = require('globby')
diff --git a/test/helpers/read.js b/test/helpers/read.js
index 3122ee1..88b6421 100644
--- a/test/helpers/read.js
+++ b/test/helpers/read.js
@@ -1,3 +1,4 @@
+'use strict'
 const { readFile } = require('fs-extra')
 
 module.exports = function (path) {
diff --git a/test/helpers/tmp.js b/test/helpers/tmp.js
index f084dea..a23fa35 100644
--- a/test/helpers/tmp.js
+++ b/test/helpers/tmp.js
@@ -1,3 +1,4 @@
+'use strict'
 const path = require('path')
 const { v4: uuid } = require('uuid')
 
diff --git a/test/map.js b/test/map.js
index ac64a78..04f90fd 100644
--- a/test/map.js
+++ b/test/map.js
@@ -1,3 +1,4 @@
+'use strict'
 const test = require('ava')
 const fs = require('fs-extra')
 
diff --git a/test/misc.js b/test/misc.js
index 29a736c..9240e32 100644
--- a/test/misc.js
+++ b/test/misc.js
@@ -1,3 +1,4 @@
+'use strict'
 const test = require('ava')
 
 const cli = require('./helpers/cli.js')
diff --git a/test/parser.js b/test/parser.js
index 4c56abb..1ac9805 100644
--- a/test/parser.js
+++ b/test/parser.js
@@ -1,3 +1,4 @@
+'use strict'
 const test = require('ava')
 
 const cli = require('./helpers/cli.js')
diff --git a/test/replace.js b/test/replace.js
index 5b48ad4..f2712a2 100644
--- a/test/replace.js
+++ b/test/replace.js
@@ -1,3 +1,4 @@
+'use strict'
 const test = require('ava')
 
 const fs = require('fs-extra')
diff --git a/test/stdin.js b/test/stdin.js
index 867145c..8709a94 100644
--- a/test/stdin.js
+++ b/test/stdin.js
@@ -1,3 +1,4 @@
+'use strict'
 const test = require('ava')
 
 const fs = require('fs-extra')
diff --git a/test/stdout.js b/test/stdout.js
index 9b26ad4..8bd5d7b 100644
--- a/test/stdout.js
+++ b/test/stdout.js
@@ -1,3 +1,4 @@
+'use strict'
 const test = require('ava')
 
 const fs = require('fs-extra')
diff --git a/test/stringifier.js b/test/stringifier.js
index 4256c79..db3ef28 100644
--- a/test/stringifier.js
+++ b/test/stringifier.js
@@ -1,3 +1,4 @@
+'use strict'
 const test = require('ava')
 
 const cli = require('./helpers/cli.js')
diff --git a/test/syntax.js b/test/syntax.js
index 4658d69..c4295f9 100644
--- a/test/syntax.js
+++ b/test/syntax.js
@@ -1,3 +1,4 @@
+'use strict'
 const test = require('ava')
 
 const cli = require('./helpers/cli.js')
diff --git a/test/use.js b/test/use.js
index 07901f6..25400f6 100644
--- a/test/use.js
+++ b/test/use.js
@@ -1,3 +1,4 @@
+'use strict'
 const test = require('ava')
 
 const cli = require('./helpers/cli.js')
diff --git a/test/watch.js b/test/watch.js
index 6012bf7..b5bce40 100644
--- a/test/watch.js
+++ b/test/watch.js
@@ -1,3 +1,4 @@
+'use strict'
 const test = require('ava')
 
 const fs = require('fs-extra')