Extra padding to leading Zeros with rendered png files?


I have a synfig file that has over 10,000 frames. I would like to add extra zero to the padding to file names.

When I use synfig to render the file to PNG files, I get a set of files from 0000 to 9999 (with leading zeros) and then another set of files from 10000 onwards. (with no leading zeros.)
This add complications to when I try to create a movie from those files using ffmpeg and even listing the file directories.

This is a sample command I use to generate my files.

 synfig -q  movie-033.sif --start-time=0m --end-time=10m  -Q 1  -o renderx/movie33.png

This is an example of the files generated.

Is there an option to add an extra zero to the file name?

Synfig version.
synfig --version
synfig 1.2.2

Running on Fedora, linux
Fedora release 30 (Thirty)