diff --git a/package.json b/package.json
index 7888abb..7b6bbeb 100644
--- a/package.json
+++ b/package.json
@@ -11,7 +11,7 @@
     "test-travis": "istanbul cover node_modules/.bin/_mocha --report lcovonly -- test.js"
   },
   "devDependencies": {
-    "assume": "~1.5.0",
+    "assume": "~2.0.0",
     "istanbul": "~0.4.5",
     "mocha": "~3.5.0",
     "negotiation": "0.0.x",