-#----- testing rebuild on input change -----
-
-echo '# for-check 1' >>../src/for-test.sd.mk
-make -j4
-grep '^# for-check 1' src/Subdir.mk || false
-
-echo '# for-check 2' >>../lib/for-test.mk.in
-make -j4
-grep '^# for-check 2' lib/for-test.mk || false
+: ----- testing rebuild on input change -----
+
+reset_times () {
+ find -type f -print0 \
+ | xargs -0 \
+ touch -hmd 'now -1 seconds' --
+}
+
+: ----- for-check-1 -----
+reset_times
+echo 'for-check-1:' >>../src/for-test.sd.mk
+make -j4 for-check-1
+grep '^for-check-1:' src/Subdir.mk || false
+
+: ----- for-check-2 -----
+reset_times
+echo 'for-check-2:' >>../lib/for-test.mk.in
+make -j4 for-check-2
+grep '^for-check-2:' lib/for-test.mk || false