tsearch2: Error: Word is too long

I tried to index my data with tsearch2 but I get the following error:

Error: Word is too long

I have looked through the docs and googled for "Word is too long" +
tsearch2 with no luck - so i hope i haven't missed something obvious.

The problem is due to binary encodings in the data, base64 etc.

Can i supply a max word length somewhere?
and how can I find out what the max limit is?

Thanks!

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