Linker error (trying to add additional feature)

I’m attempting to write an additional stretching filter for siril based on an idea in the Astrobin forums by David Payne (see the link at the bottom for details). The code is done (based off asinh.c) except for the command-line glue I need to put into command.c, and I’ve added an additional dialog to My code compiles ok, but fails at the linker stage with the following:

/usr/bin/ld: src/libsiril.a.p/gui_dialogs.c.o:( undefined reference to `apply_payne_cancel’

But I have defined void apply_payne_cancel() in my additional header file payne.h, which is included in dialogs.c

Is there something obvious I’m missing?

did you add your file in and

Pretty sure I added it in Makefile am but possibly not in the meson file. Meson is new to me since I last wrote any code. I’m away now but I’ll check that when I get home in a day or so. Thanks!