In Hefferin v. Scott Realty Co., 71 Wyo. 114, 254 P.2d 194 (1953), the Court examined the common-law rules of landlord liability. In that case, a tenant sued her landlord for injuries resulting from the landlord's improper furnishing of ventilation in the leased premises. 254 P.2d at 194. The parties' lease did not contain any provisions which referenced an obligation on the landlord's part to make repairs. 254 P.2d at 195. The Court held that, in the absence of an agreement to the contrary, a landlord is not obligated to make repairs upon the leased premises during the lease period whether the defects existed at the time he leased the premises or occurred thereafter. 254 P.2d at 197. This is so even if the premises are in a dangerous condition. Id. This principle is based on the theory that a landlord should not be liable for defects in the leased premises where he has not made any warranty or contract as to the condition of those premises or as to the repair of defects and is guilty of no willful wrong or fraud. Id. Essentially, the duty to repair arises out of the existence of the contract to repair; therefore, the contract defines the extent of the duty. Montelongo v. Goodall, 788 S.W.2d 717, 719 (Tex. App. 1990). In Hefferin, the tenant did not rely on a contract contained in the lease, but instead she alleged the landlord made a promise to properly install a new ventilation system. 254 P.2d at 197. In response to the tenant's claim, the Court held the landlord is under no obligation to make repairs unless such a stipulation is made a part of the original contract or any subsequent promise to make repairs is supported by consideration and not founded merely on the relation of the parties. Id. Sufficient consideration exists when a tenant, who is not bound to a term of tenancy, relies upon a landlord's promise to make repairs made to induce the continuation of the tenancy. Id. However, in Hefferin, the tenant agreed to a definite three-year lease term, and the Court concluded there was no new consideration present for a promise or contract. Thus, the promise made by the landlord was wholly gratuitous, and therefore the landlord could not be liable. Id. Moreover, the Court held that a landlord's agreement to make repairs must take the form of an express contract and should not be implied from the parties' conduct. Id.