Missing separator in .DELETE_ON_ERROR ?

[Felix Lechner via Users list for the GNU implementation of make]

Hi,

Why does the file below produce this error on GNU Guix, please?

    Makefile:1: *** missing separator.  Stop.

Kind regards
Felix

P.S. I do not subscribe to your list, so please copy me.  Thanks!

* * *

.DELETE_ON_ERROR

all:
    echo "Hello"