Celtic punk band Dropkick Murphys are not pleased that Wisconsin governor Scott Walker has chosen to use their song for political purposes.

The likely 2016 presidential candidate played their song “I’m Shipping Up To Boston” during an entrance at the Iowa Freedom Summit this past Saturday. Following that, the band tweeted:

The beef goes back to 2011, when Walker put to action a bill that limited the collective bargaining rights of unions. The band responded by selling pro-union t-shirts on their website.