Index: package.json
diff --git a/package.json b/package.json
index 4656e9cb04173ec9adbaeab1a1e7c6a5f10eb7ce..d02d620e997056bd319af9755f769cc3f8a5b9be 100644
--- a/package.json
+++ b/package.json
@@ -3,6 +3,10 @@
   "repository": "https://hg.adblockplus.org/buildtools",
   "license": "MPL-2.0",
   "dependencies": {
+    "//": [
+      "'acorn' is a peer dependency of manifoldjs, we don't use it otherwise."
+    ],
+    "acorn": "^6.0.0",
     "jsdoc": "3.5.5",
     "manifoldjs": "0.7.6",
     "memory-fs": "0.4.1",