A method, an apparatus, and a computer-readable medium for wireless communication are provided. The apparatus may be a base station. The apparatus may transmit a first grant to a UE. The apparatus may determine whether an acknowledgment to the first grant is received. When the acknowledgment to the first grant fails to be received by the apparatus, the apparatus may transmit, to the UE, a second grant including information regarding the first grant. In another aspect, an apparatus may be a UE. The apparatus may receive a first grant. The first grant may include a first Mayday bit. The apparatus may receive a second grant. The second grant may include a TTI count corresponding to a number of unacknowledged TTIs. The second grant may further include a second Mayday bit. The apparatus may determine an acknowledgment based on the TTI count and the first and second Mayday bits.