diff --git a/lib/mongodb/gridfs/gridstore.js b/lib/mongodb/gridfs/gridstore.js
index 95114b1462..a3d9ab59e3 100644
--- a/lib/mongodb/gridfs/gridstore.js
+++ b/lib/mongodb/gridfs/gridstore.js
@@ -103,7 +103,7 @@ var GridStore = exports.GridStore = function(db, fileIdObject, mode, options) {
  */
 GridStore.prototype.open = function(callback) {
   if( this.mode != "w" && this.mode != "w+" && this.mode != "r"){
-    callback(new Error("Illegal mode " + self.mode), null);
+    callback(new Error("Illegal mode " + this.mode), null);
     return;
   }