diff --git a/package.json b/package.json
index c7965db32..54277349c 100644
--- a/package.json
+++ b/package.json
@@ -38,7 +38,7 @@
     "broccoli-debug": "^0.6.5",
     "broccoli-filter": "^1.3.0",
     "broccoli-funnel": "^3.0.3",
-    "broccoli-merge-trees": "^3.0.2",
+    "broccoli-merge-trees": "^4.2.0",
     "broccoli-persistent-filter": "^2.3.1",
     "broccoli-plugin": "1.3.1 - 3",
     "broccoli-source": "^3.0.0",