General Discussion - 长臂猿

Okay, so to go along with my gradual emergence from lurkerdome I figured I should have a somewhat cleverer screen name than my own name minus the spacing and capitalization.

So I'm going with the name that was given to me by an (American) friend I had in China. I was pleasantly surprised to find that I could change my username here without any hassle. So 长臂猿 (cháng bèi yuán) it is.

However when looking up that pinyin above on my much-loved Chinese annotation tool, I saw that 臂 came up as bèi rather than its usual bì. Can anyone confirm whether that is correct? Did the aforementioned friend christen me with a name he never pronounced correctly?

Incidentally, the name translates to "gibbon" which is close to my English surname.