APIError(code=401): signature verification failed because of / in the memo

[frouxcois]

Hello,
I have an issue when broadcasting my transactions with the following error : "APIError(code=401): signature verification failed"
After investigation, I've found that the "/" in my memo is responsible of it (the broadcast works when I delete the slash)
Do you know how what should I do to broadcast this transaction with the "/" in the memo ?