Result out of range

[Derpford]

I tried setting things up with a simple example:

include 1991.fs

\ Default route, hello world!
: handle-/ s" Hello, 1991." ;

/1991 / handle-/

80 1991:

However, instead of producing "Hello, 1991" upon loading the page, I instead get an error:

in file included from *OS command line*:-1
1991-test.fs:8: Result out of range
80 >>>1991:<<<
Backtrace:
$769265D0 um/mod 
$76926CE0 ms@ 
$769283E8 read-socket 
$B15E68 
$76928AB8 read-request 
$76928B10 start-server