Arabic is set to become the second largest first language in Sweden, with Finnish being overtaken for the first time in history.
Finnish has been the most commonly spoken non-Swedish mother tongue for more than 1,000 years, but it is now set to come in third.
This is a result of an ageing Finnish-speaking population and the influx of migrants and refugees from Arabic-speaking nations in recent years, researchers say.
Finnish as the second largest language spoken in Sweden has deep roots in the history of both countries.
Finland was part of the Kingdom of Sweden for 560 years, until 1809 when Sweden effectively handed over the country to Russia as part of the peace deal that ended the Finnish War.
But even 150 years after after the separation, a large number of Finnish migrants continued to arrive in Sweden, and in 2012, an estimated 200,000 people had Finnish as a first language.
However, with native Finnish speakers ageing and the new generation of migrants coming from further afield, it is estimated that Arabic is due to take over in the next few years.
'Most speakers of Finnish are also immigrants. But they came several decades ago and are now dying,' Professor Mikael Parkvall, a linguist at Stockholm University, told Sveriges Radio.
'They have to some extent passed the language on to their children but not to the extent that it would compensate for their own deaths.'
More than 155,000 people in Sweden spoke Arabic as their first language in 2012, a number which is expected to have grown exponentially since.
In 2015 alone, Sweden welcomed 165,000 migrants and refugees, many of them from Arabic-speaking nations.
Mr Parkvall has therefore concluded that unless it is already the case, Arabic is soon to be the second most common mother tongue in Sweden.
However, he stresses that this conclusion is based on his own research, and not on official first-language statistics as there is no such thing in Sweden.
Authorities in the Scandinavian nation has ruled that registration of mother tongues would be too close to ethnic registration, Parkvall said.