It was decided in Wills v. Manufacturers’ Natural Gas Co., 130 Pa. 222 and Westmoreland, etc., Natural Gas Co. v. DeWitt, 130 Pa. 235, that a clause in a lease that it shall be null and void on failure of the lessee to pay rent or keep other covenants, is not self-operating so as to make the lease void ipso facto by the default, but being a provision for the benefit of the lessor may be enforced or waived at his option. These cases have been followed by many others down to Bartley v. Phillips, 179 Pa. 175.

It hardly required more then a glance at the reason of the thing to show the applicability of this principle to the present case. Appellant became surety to the plaintiff for the punctual payment by the lessee of rent amounting to $5,000. The claim now made is that the lessee by his own default could release his surety from all liability beyond the first thousand dollars. Such a construction would reduce the security to the plaintiff to just one fifth of the'sum the contract expressly stipulates for. While parties may, as was said in Wills v. Gas Co., supra, contract that on a default the lease may become void at the option of either party, yet such intent in *109the agreement must be so plain as to be unavoidable, in order to sustain such a construction.

The other question raised is equally untenable. There was not only no tender of a partial payment of the rent due, but not even a clear offer, merely a reference to the amount of money the lessee had in bank which was available on the rent account. This was much too vague and uncertain to reduce the liability even of a surety.

Judgment affirmed.