Change of original citizenship after become a Canadian PR

[letina]

My sister married a US citizen and she was in the naturalization process before becoming a US citizen while she got her Canadian PR approved (she applied as skill worker many years ago). She landed in Canada and received her PR card wihch states that she is a citizen of country X. Now her US citizenship is approved and she changed her citizenship to US citizen, what will happen to her Canadian PR? Her PR card show that she is a citizen of country X but now she is a US citizen, so is the card still valid?

[Leon]

Next time she enters Canada, she should bring her old invalid passport and her US passport and tell the immigration officers that she has changed her citizenship.  She can apply for it to be corrected on her PR card as well.  However, she needs to keep in mind that she needs to live in Canada at least 730 days in any 5 year period to keep her PR.