Arithmetic expansion through ssh and zsh -lc throws parse error

I’m attempting the following:

❯ ssh user1@10.8.1.1 zsh --version
zsh 5.8.1 (x86_64-apple-darwin22.0)

❯ ssh user1@10.8.1.1 zsh -lc "for ((index=1; index <= 1; index++)); do echo \$index; done"
zsh:1: parse error near `)'

Yet locally and also without zsh -lc through ssh, it works:

❯ zsh -lc "for ((index=1; index <= 1; index++)); do echo $index; done"
1
❯ ssh user1@10.8.1.1 "for ((index=1; index <= 1; index++)); do echo \$index; done"
1

I can also get it to work when I do anything before the for loop:

❯ ssh user1@10.8.1.1 zsh -lc "echo 1; for ((index=1; index <= 1; index++)); do echo \$index; done"

1

Any recommendations on where I should look?

>Solution :

There’s also word splitting by the destination shell which you want to avoid. So quoting once more should work:

ssh user1@10.8.1.1 zsh -lc "'for ((index=1; index <= 1; index++)); do echo \$index; done'"