diff --git a/ftpd.js b/ftpd.js
index 4c63876..5e3b2e6 100755
--- a/ftpd.js
+++ b/ftpd.js
@@ -36,7 +36,10 @@ function fixPath(fs, path) {
 }
 
 // host should be an IP address, and sandbox a path without trailing slash for now
-function createServer(host, sandbox) {
+function createServer(host, sandbox, virtualFS) {
+    if(virtualFS){
+    	fs = virtualFS;
+    }
     // make sure host is an IP address, otherwise DATA connections will likely break
     var server = net.createServer();
     server.baseSandbox = sandbox; // path which we're starting relative to