A note on right-angled Artin subgroups of one-relator groups

We give a short proof of the following result due to Howie: if $A(\mathrm{\Gamma })$ is a right-angled Artin group embedding into some one-relator group, then $\mathrm{\Gamma }$ is a finite forest. The proof only uses elementary Bass–Serre theory and classical properties of one-relator groups.