diff --git a/package.json b/package.json
index 93dcbde..a861761 100644
--- a/package.json
+++ b/package.json
@@ -74,6 +74,7 @@
   },
   "devDependencies": {
     "@arethetypeswrong/cli": "^0.18.2",
+    "@types/natural-compare": "^1.4.3",
     "@types/node": "^20.19.0",
     "c8": "^11.0.0",
     "dedent": "^1.5.3",
@@ -86,7 +87,7 @@
     "mdast-util-from-markdown": "^2.0.2",
     "mocha": "^11.3.0",
     "prettier": "3.8.1",
-    "typescript": "^5.9.3",
+    "typescript": "^6.0.2",
     "yorkie": "^2.0.0"
   },
   "engines": {
diff --git a/src/index.js b/src/index.js
index 5599533..c9b7310 100644
--- a/src/index.js
+++ b/src/index.js
@@ -36,10 +36,7 @@ const plugin = {
 	},
 };
 
-// eslint-disable-next-line no-lone-blocks -- The block syntax { ... } ensures that TypeScript does not get confused about the type of `plugin`.
-{
-	plugin.configs.recommended.plugins.json = plugin;
-}
+Object.assign(plugin.configs.recommended.plugins, { json: plugin });
 
 export default plugin;
 export { JSONSourceCode };
diff --git a/tests/types/tsconfig.json b/tests/types/tsconfig.json
index 373f9d7..14eb608 100644
--- a/tests/types/tsconfig.json
+++ b/tests/types/tsconfig.json
@@ -4,6 +4,8 @@
     "noEmit": true,
     "rootDir": "../..",
     "strict": true,
+    "strictNullChecks": true,
+    "useUnknownInCatchVariables": true,
     "exactOptionalPropertyTypes": true,
     "verbatimModuleSyntax": true,
     "erasableSyntaxOnly": true
diff --git a/tsconfig.json b/tsconfig.json
index d52d3f9..24ed175 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -8,6 +8,9 @@
     "target": "ESNext",
     "moduleResolution": "NodeNext",
     "module": "NodeNext",
+    "rootDir": "./src",
+    "strictNullChecks": false,
+    "useUnknownInCatchVariables": false,
     "types": []
   }
 }