Set mode-only flags

Is it possible to pass custom flags for specific modes? For example, dune file below works for dune build main.exe but fails for dune build main.exe.o because ocamlopt does not expect -lfoo. Is there a way to set -lfoo only for exe mode and not for object mode?

Problematic example:

(executable
   (name main)
   (libraries base core ctypes ctypes.foreign ctypes.stubs)
   (link_flags (-cclib -lfoo))
   (modes object exe))

Thanks!