WASHINGTON — It took longer than they expected, but Chipotle has removed all genetically modified ingredients from its menu.

The chain has been working for two years to get GMOs — genetically modified organisms — out of crops that make it into their ingredients, MarketWatch reports.

Chipotle began telling customers which of its offerings contained GMOs in 2013, and a spokesman for the chain says that the transition “took a little longer than we thought.” They were looking for substitutes for GMO tortillas and soybean oil.

The Food and Drug Administration has approved some GMO crops, saying the changes in the plants’ DNA helps them do things such as ward off pests. But critics have been suspicious of the technology, and MarketWatch reports that Chipotle founder and co-CEO Steve Ells has said the company wants to avoid GMOs until the science on the possible effects is more definitive.