Using tabs instead of spaces

I am trying to format a program's source code with GNU Indent, and I would
like to have it indented using the GNU style, except for the spaces.

I am using --use-tabs (which according to the documentation is on by
default) but indentation is still done using 2 spaces.

How can I tell indent to use tabs instead of spaces for indentation?

Thanks in advance for your help,

Joe R. Nassimian