'$(MAKE) target' may not work if the top-level Makefile has an uncommon name

Hello,

Maybe I oversaw something, but I think, it should work. What I do:

/----- notCalledMakefile -----
# a Makefile, that isn't called Makefile

include foo.make

test-foo: foo

bar:
	$(MAKE) foo
\--------------------

/----- foo.make -----
# foo.make

foo:
	@echo "Just a test."

\--------------------

If I try to call the bar target, I get the error:

$ make -F notCalledMakefile bar
make foo
make[1]: Entering directory `/home/dl/test/make'
make[1]: *** No rule to make target `foo'.  Stop.
make[1]: Leaving directory `/home/dl/test/make'
make: *** [bar] Error 2

But if I rename this file to Makefile, everything works. Is this
intended behaviour? If yes, why? Where can I read more about it? The
current workaround is to set MAKEFILES += $(CURDIR)/notCalledMakefile to
make this work.

Regards, Daniel