diff --git a/tutorial/nodejs/NodeServer.js b/tutorial/nodejs/NodeServer.js
index ba36105..55d3817 100644
--- a/tutorial/nodejs/NodeServer.js
+++ b/tutorial/nodejs/NodeServer.js
@@ -48,7 +48,7 @@
     } else if (work.op === ttypes.Operation.DIVIDE) {
       if (work.num2 === 0) {
         var x = new ttypes.InvalidOperation();
-        x.what = work.op;
+        x.whatOp = work.op;
         x.why = 'Cannot divide by 0';
         result(x);
         return;
@@ -56,7 +56,7 @@
       val = work.num1 / work.num2;
     } else {
       var x = new ttypes.InvalidOperation();
-      x.what = work.op;
+      x.whatOp = work.op;
       x.why = 'Invalid operation';
       result(x);
       return;