The termination clause here is clearly a condition subsequent, 49 Am.Jur.2d, Landlord and Tenant, §§ 998, et seq., pp. 969, et seq. Compare Medical West Building Corp. v. E.L. Zoernig & Co., 440 S.W.2d 744 (Mo.1969), where there was a fact issue as to whether a building manager had been terminated by lessor, which, if established, would give lessee an option to terminate the lease in accordance with an express clause for termination in the event that lessor fired the building manager. The clause is one that appellant had the right to insist upon to protect itself from any possibility that the city would seek to enforce the zoning provisions, thus putting appellant out of business because of inability to furnish the required parking in the future. The clause takes on special significance when the options to purchase and to renew the lease are considered. If respondents were not required to take “immediate action” to correct the situation, appellant might be deemed to have waived the provision, and would be saddled with the premises not in conformity with parking ordinances, for the first year, or thereafter, if the lease were renewed or the option to purchase were exercised. Note also Sachs Steel & Supply Co. v. St. Louis Auto Parts and Salvage Co., 322 S.W.2d 183 (Mo.App.1959), which, although holding that a lessee could not abandon a lease because zoning laws prohibited lessee’s planned use of the premises, it being presumed to have knowledge of the zoning restriction, noted at page 187, “Had [the] lessee desired to protect itself against the possibility that the intended use of any portion of the premises might be prohibited by prevailing zoning ordinances, * * * it could have refused to execute the lease or insisted that the lease contain conditional clauses or termination privileges based upon these contingencies.”