diff --git a/tutorial/rb/RubyServer.rb b/tutorial/rb/RubyServer.rb
index ea39e15..60d019f 100755
--- a/tutorial/rb/RubyServer.rb
+++ b/tutorial/rb/RubyServer.rb
@@ -42,7 +42,7 @@
       end
       val = work.num1 / work.num2
     else
-      x = InvalidOperation()
+      x = InvalidOperation.new()
       x.what = work.op
       x.why = "Invalid operation"
       raise x