Error building tk9.0.1: No rule to make target 'minizip'

I get the following error when trying to build tk9.0.1
under Debian 11:
make: *** No rule to make target 'minizip', needed by 'libtk9.0.1.zip'.  Stop.
During configure the log says:
...
checking for macher... checking for zip... No zip found on PATH. Building minizip
...
I'm building with --prefix and there is no zip installed on this system.
So configure concluded it has to build its own (mini)zip,
but... there doesn't seem to be a minizip in tk.
In the tcl9.0.1 tarball, on the other hand, a compat/minizip is available
(and build).
Any suggestions?
Thanks in advance
Uwe