How can I make rice protein smoothies less gritty?

I have some plain rice protein powder that I've been using for fruit smoothies (a cup of orange juice, some frozen strawberries, and a half scoop of the powder) but I find that it's really gritty, even when I blend it for a long time. I tried adding a bit of almond milk, but that didn't work. Does anyone know how I can make it smoother and less chalky and gritty?