diff --git a/package.json b/package.json
index e1e2eb2..ed5b04d 100644
--- a/package.json
+++ b/package.json
@@ -30,6 +30,7 @@
     "@types/mocha": "^5.2.7",
     "aegir": "ipfs/aegir#feat/cosmiconfig",
     "chai": "^4.2.0",
+    "karma-mocha-webworker": "^1.3.0",
     "mocha": "^6.2.2",
     "sinon": "^8.1.0"
   },