diff --git a/app/models/qbo_invoice.rb b/app/models/qbo_invoice.rb
index b534a1e..39bd15c 100644
--- a/app/models/qbo_invoice.rb
+++ b/app/models/qbo_invoice.rb
@@ -150,7 +150,7 @@ class QboInvoice < ActiveRecord::Base
     # TODO Add some hooks here
 
     # Push updates
-    invoice.sync_token = invoice.sync_token +1 if is_changed
+    invoice.sync_token += 1 if is_changed
     get_base.update(invoice) if is_changed
   end