diff --git a/package.json b/package.json
index e1f5eff..36994db 100644
--- a/package.json
+++ b/package.json
@@ -41,6 +41,6 @@
   "devDependencies": {
     "ava": "^8",
     "tsd": "^0.33",
-    "xo": "^3.0"
+    "xo": "^4.0"
   }
 }