Channel 4 has updated its All 4 catch-up app for iOS, adding subtitles to shows.
That means the deaf and hearing impaired will be able to enjoy Channel 4 programs on-demand and on catch-up.
The app also now features improvements to its VoiceOver navigation, and the ability to watch programmes from your mobile device on your TV using Google Chromecast.
The Android app has also been updated, and now features the Chromecast functionality. However, it doesn't have subtitles.
Rachel Yendoll, Channel 4's head of content management, said: "We know there's been a strong demand to provide subtitles on the iOS platform, people can now enjoy watching C4 programmes with subtitles on their iPhones and iPads and we're delighted that this service is now live.
"We are one of the leading broadcasters in terms of accessibility and we're looking forward to rolling out more accessibility features on more platforms in the coming months."
According to the most recent ATVOD (Authority for Television on Demand) survey, 99 per cent of Channel 4 shows had subtitles, compared to 92 per cent in 2013.