According to a label filed with the Alcohol and Tobacco Tax and Trade Bureau (TTB), Odell Brewing Co. is working on releasing Bull Proof, an imperial stout aged in freshly emptied bourbon barrels sourced from Fort Collins, Colo.-baed Old Elk Distillery. The new stout will be the latest addition to Odell’s Cellar Series, which is made up of beers that are made with the brewery’s pilot system, with some “brewed in the name of research, some are envelope pushers, and some are just for fun.”

“A bourbon barrel stout is, by design, an exercise in collaboration,” reads the beer label. “When Old Elk Distillery opened its doors less than a mile from our brewery, back of napkin sketches were traded, and after months of patience, this imperial stout is realized.”

Bull Proof Bourbon Barrel Stout will be packaged in 12-ounce bottles and is scheduled to be released in 2018. An email sent to the brewery for additional information was not immediately returned.