Prevent alias with `find` from running at login

How do I make an alias in .bashrc with sub-commands?

Right now I have:

alias pngc="for file in \`find \$1 -name \"*.png\"\`; do pngcrush -brute \"\$file\" temp.png; mv -f temp.png \$file; done"

If I enter this in a shell, the alias is registered correctly and I can run it correctly. However, if I add this to .bashrc, (parts of) it runs at login, which I know because it hangs for a huge amount of time, probably because it's find-ing in my entire home directory.

(Not a duplicate of this or that)

Edits based on comments:

Attempt:

alias pngc="for file in ./*.png; do pngcrush -brute \"\$file\" temp.png; mv -f temp.png \$file; done"

Could not find file: ./*.png
Could not find file: temp.png

(temp is the current directory)

Attempt:

alias pngc="for file in ./*.png; do [[ -f \"\$i\" ]] || continue; pngcrush -brute \"\$file\" temp.png; mv -f temp.png \$file; done"

Does nothing!