CHR / CHR$ issue? (*solved*)

[britlion]

I boiled the issue down to the following code

Code:

DIM x,f as integer
    CLS
    FOR x=1 TO 4
      PRINT AT 0,0;
      LET f=1
170   print at 0,0;
      PRINT (x+64);
      IF f<704 THEN
        LET f=f+1
        GO TO 170
      END IF
180 NEXT x
    BEEP 1,1

This works perfectly. However, if we ask for the CHR of (x+64):

Code:

DIM x,f as integer
    CLS
    FOR x=1 TO 4
      PRINT AT 0,0;
      LET f=1
170   print at 0,0;
      PRINT CHR(x+64);
      IF f<704 THEN
        LET f=f+1
        GO TO 170
      END IF
180 NEXT x
    BEEP 1,1

My produced code crashes spectacularly. Has the CHR function come up with a bug?