As The mistake was performed from the god Indra, he grants Hanuman a want that his system would be as sturdy as Indra's Vajra, and that his Vajra may not hurt him. In addition to Indra other gods have also granted him wishes: the God Agni granted Hanuman a desire https://medium.com/@HinduTempleAdelaide/where-courage-meets-karma-the-spiritual-harmony-of-hanuman-mandir-south-australia-e6673001175d