The question is whether the waiver of the right not to be sued for twelve months can be revoked. It is settled that exemption from suit afforded an administrator may be waived. Emmett & Co. v. Dekle, 132 Ga. 593 (64 SE 682); Leath v. Hardman, 43 Ga. App. 270 (158 SE 453). It appears that the defendant voluntarily and intentionally waived his right to be exempt from suit for the statutory period. In Sentinel Fire Ins. Co. v. McRoberts, 50 Ga. App. 732 (179 SE 256), a case concerning the waiver of proof of loss as stipulated in an insurance policy, this court held that once a waiver has been made with knowledge of the facts and in the absence of fraud, it cannot be withdrawn. See 92 CJS 1041, 1069, Waiver. We see no reason why this rule should not apply to the waiver in this instance. There is no issue raised here as to fraud or that defendant did not have knowledge of the facts. The contention that the defendant received no consideration for the waiver is without merit as consideration is not an essential of waiver. Gray Lumber Co. v. Harris, 8 Ga. App. 70 (68 SE 749).