Crashes when file path for xmlParse has backslashes

[rjt2000-Rain]

I was trying to run:
engine.Evaluate("file <- xmlParse(\"filepath\\with\\backslashes\")");

and it would crash at line 963 in the REngine.cs file, when trying to parse the line or something.
Replacing the backslashes with forward slashes before the call fixed it, but the error message only gave me a memory address and the thread id, so it took 2 days to diagnose...