With free cash flows, borrowers can accumulate cash or voluntarily pay down debts. However, sometimes creditors impose a mandatory repayment covenant called "excess cash flow sweep" in loan contracts to force borrowers to repay debts ahead of schedule. About 17 percent of borrowers in the authors' sample (1995-2006) have this covenant attached to at least one of their loans. The author finds that the sweep covenant is more likely to be imposed on borrowers with higher leverage (i.e., where risk shifting by equity holders is more likely). The results are robust to including borrower fixed effects or using industry median leverage as a proxy. The covenant is more common also in borrowers where equity holders appear to have firmer control, e.g., when more shares are controlled by institutional block holders, when firms are incorporated in states with laws more favorable to hostile takeovers, or when equity holders place higher valuation on excess cash holdings. These determinants suggest that the sweep covenant may be motivated by creditor-shareholder conflicts. Finally, the author shows that the covenant has real effects: borrowers affected by the sweep covenant indeed repay more debts using excess cash flows, and they spend less in capital investment and pay out fewer dividends to shareholders.