diff --git a/lib/filesystem.js b/lib/filesystem.js
index 7283dcf..908b0dd 100644
--- a/lib/filesystem.js
+++ b/lib/filesystem.js
@@ -51,7 +51,7 @@ class Filesystem {
     if (shouldUnpack) {
       node.unpacked = shouldUnpack
     }
-    node.files = {}
+    node.files = node.files || {}
     return node.files
   }