Space character with custom charset

[vagantis]

Code:

hashcat64.exe -a 3 -m 10500 -w 4 -D 2 -1 ?d\ _,.-/:  -o found_pdf.txt hash_pdf.txt ?1?1?1?1?1?1?1?1?1?1?1?1?1 --increment

Somehow, when I type this command, I get the following exception.

Code:

Hash '_,.-/:': Line-length exception

No hashes loaded

It looks like proceeding space with \ doesn't work in arg list. What am I doing wrong?