Thanks, wouldn't the following be a bit cleaner,
since MAINTAINERCLEANFILES contains BUILT_SOURCES?
diff --git a/src/local.mk b/src/local.mk
index 02a9bf5..ead3b8b 100644
--- a/src/local.mk
+++ b/src/local.mk
@@ -385,7 +385,7 @@ src/dircolors.h: src/dcgen src/dircolors.hin
# built only if absent. It is not cleaned because we don't want to
# insist that maintainers must build on hosts that support the widest
# known ints (currently 128-bit).
-MAINTAINERCLEANFILES += $(top_srcdir)/src/primes.h
+BUILT_SOURCES += $(top_srcdir)/src/primes.h
$(top_srcdir)/src/primes.h:
$(MAKE) src/make-prime-list
$(AM_V_GEN)rm -f $@ $@-t
