H I SHORT SPACING CORRECTION The THINGS H I data cube for M101 is seriously affected by filtering and bowling artifacts. The red spectrum illustrates the spectrum for an arbitrarily selected line of sight at 650′ spatial resolution (angular resolution of the Effelsberg single-dish data). The black spectrum shows the same sightline spectrum obtained from the Effelsberg single-dish data (EBHIS survey). We used the uvcombine package to determine a single-dish scale factor of 1.7. The blue spectrum shows the resulting feathered observation for the selected sightline.