The US embassy in Nigeria has announced that it is no longer accepting visa renewal applications via international courier service DHL.

As of May 14, Nigerians seeking to get US non-immigrant visas must apply online and will be required to appear in-person at the US Embassy in Abuja or US Consulate General in Lagos.

The U.S. Mission said it is taking this step to provide more efficient customer service and promote legitimate travel. The new changes apply to future applicants. Nigerians who have already started the so-called “Dropbox” visa application process via to DHL will be processed.

The change also comes one month after news that Trump administration has been considering new immigration measures to impose visa restrictions on countries whose citizens have a track record of overstaying beyond the validity of their short-term US visas. Nigeria accounted for the third highest number of US visa overstays last year.

The proposed measures included reducing visa validity periods, making it tougher for citizens from countries like Nigeria to receive visas at all and the long-term possibility of outright bans.