diff --git a/package.json b/package.json
index dfec63c..8a96678 100644
--- a/package.json
+++ b/package.json
@@ -31,7 +31,7 @@
   },
   "devDependencies": {
     "c8": "8.0.x",
-    "oletus": "3.2.x",
+    "oletus": "4.0.x",
     "sanctuary-scripts": "5.0.x"
   },
   "scripts": {