Letter of recommendation from non-native speaker I am currently a PhD student in theoretical computer science applying for postdoc positions in Europe and the US that will start next year. Apart from my advisor's, I will also include a letter of recommendation (LOR) from a professor with whom I have published several articles. The problem is that while he is an accomplished researcher in his field and let me know that he thinks highly of me, his command of the English language outside the scientific realm shows some major flaws and I have reason to expect that this will also reflect in an LOR. Now I am worried that this will affect any impression the LOR will make towards the negative. 

Is this justified? How likely is it that an otherwise excellent LOR will be viewed negatively by a selection committee because of bad grammar/clumsy expressions?

Edit: A good answer for the US has been given, but I am also curious how it differs from Europe.
USA Grad Schools Answer:

Spelling and grammatical errors are ignored - especially if we know the letter writer is not a native speaker. The letters are letters, not published, peer-reviewed journal articles.

What is usually more problematic with academics who didn't come out of American systems (or who haven't been here long) is that they don't fit the genre form of American letters of recommendation - which is excessively flourished praise over several pages with minutiae of biographic details and research insights.

I have read many letters from colleagues at foreign universities that are just three sentences long. This won't work. One of my American colleagues at my previous workplace regularly wrote letters that were 5-6 pages long. I think that's excessive. Somewhere in between is the sweet spot.

If your professor has been here long enough and gone through grad admissions at an American school, they will know what it takes to get in. I wouldn't worry about the grammar and spelling, though. As long as it comes in on letterhead and/or through the portal, we assume it's genuine. And if it's too opaque, we're known to actually phone letter writers to verify the authenticity or clarify the contents of a recommendation.