diff --git a/bumblebee/engine.py b/bumblebee/engine.py
index 377dfc4..fd3bbe9 100644
--- a/bumblebee/engine.py
+++ b/bumblebee/engine.py
@@ -295,11 +295,14 @@ class Engine(object):
             self._current_module = module
             module.update_wrapper(module.widgets())
             if module.error is None:
-                widget_ids = module.parameter('id', '').split(',')
+                widget_ids = []
+                if module.parameter('id'):
+                    widget_ids = module.parameter('id').split(',')
                 idx = 0
                 for widget in module.widgets():
                     widget.link_module(module)
-                    widget.id = widget_ids[idx] if idx < len(widget_ids) else widget.id
+                    if idx < len(widget_ids):
+                        widget.id = widget_ids[idx]
                     idx = idx + 1
                     self._output.draw(widget=widget, module=module, engine=self)
             else: