SQLite Slash as first Character in Value

I found some strange behaviour in SQLite when joining two tables with a value starting with a forward slash:

table_a_value = '/a/b/c/d/'

After joining table_a_value into another table, the forward slash at the beginning is lost:

result after join = 'a/b/c/d/'

What can I do for it not to delete the first character '/'?