Following the camera-ready deadline for the version of this work published at POPL 2012 [Naden et al., 2012], we found two flaws in the proof claimed in the paper. First, there was a soundness issue with regards to the handling of source location lists generated by match expressions. Second, the invariants for the proof of soundness were found to be insufficient. As a soundness issue, the first flaw was more serious; however, it was not an issue with the core borrowing contributions of the paper per se, but rather with how borrowing interacts with the match construct in our language. The technical report version, Carnegie Mellon Computer Science Technical Report CMU-CS-11-142, describes a change to the rules for match that restores soundness, and in addition substantially simplifies the proof. A detailed explanation of the fix is included in section 3.6 of the technical report.