Nothing ruins the cheery spirit of holiday decorating quicker than stringing up holiday lights only to find that — click —one burned-out bulb has ruined the whole bunch. It’s a pitfall that comes back to haunt us year after year like the Ghost of Christmas Past, along with forgetting to buy a gift for that one coworker and burning the holiday cookies. But a new tool puts an end to that no-fun holiday tradition: The LightKeeper Pro ($30) is an unassuming handheld gadget that detects and repairs defective bulbs.

This all-in-one tool is basically a full-service repair shop for your string lights. You can use the top to test individual bulbs or see if there’s still juice in your fuse. The handle acts as a storage compartment for spare replacement pieces, and most remarkable of all, a few pulls of the trigger can make a mysteriously malfunctioning string of lights shine like new. Just plug the nozzle into any bulb on the unlit strand, click a few times, and the LightKeeper Pro will fix the interrupted current so the strand will light again. From there, you’ll be able to see which individual bulb is malfunctioning.

But it’s not just for decking the halls. The LightKeeper Pro is well-suited for outdoor decorating projects too. The audible voltage sensor feature makes it easy to tell where you’re losing the current on icicle lights and landscaping net lights. Oh, and it can even handle pre-lit trees. All in all, this tool seems indispensable for the holiday season ahead.

At $30, we’re sure this gadget will pay for itself in the time (and frustration!) it saves after just one year. To put it another way, it’s the key to a merrier Christmas.

Need some inspiration for your holiday decorating? Follow us on Pinterest for tons of seasonal tips.

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(Photos via LightKeeper Pro)