diff --git a/t/t7704-repack-cruft.sh b/t/t7704-repack-cruft.sh
index 8aebfb45f5..2b0a55f8fd 100755
--- a/t/t7704-repack-cruft.sh
+++ b/t/t7704-repack-cruft.sh

@@ -724,4 +724,94 @@ test_expect_success 'cruft repack respects --quiet' '
 	)
 '
 
+setup_cruft_exclude_tests() {
+	git init "$1" &&
+	(
+		cd "$1" &&
+
+		git config repack.midxMustContainCruft false &&
+
+		test_commit one &&
+
+		test_commit --no-tag two &&
+		two="$(git rev-parse HEAD)" &&
+		test_commit --no-tag three &&
+		three="$(git rev-parse HEAD)" &&
+		git reset --hard one &&
+		git reflog expire --all --expire=all &&
+
+		GIT_TEST_MULTI_PACK_INDEX=0 git repack --cruft -d &&
+
+		git merge $two &&
+		test_commit four
+	)
+}
+
+test_expect_success 'repack --write-midx excludes cruft where possible' '
+	setup_cruft_exclude_tests exclude-cruft-when-possible &&
+	(
+		cd exclude-cruft-when-possible &&
+
+		GIT_TEST_MULTI_PACK_INDEX=0 \
+		git repack -d --geometric=2 --write-midx --write-bitmap-index &&
+
+		test-tool read-midx --show-objects $objdir >midx &&
+		cruft="$(ls $packdir/*.mtimes)" &&
+		test_grep ! "$(basename "$cruft" .mtimes).idx" midx &&
+
+		git rev-list --all --objects --no-object-names >reachable.raw &&
+		sort reachable.raw >reachable.objects &&
+		awk "/\.pack$/ { print \$1 }" <midx | sort >midx.objects &&
+
+		test_cmp reachable.objects midx.objects
+	)
+'
+
+test_expect_success 'repack --write-midx includes cruft when instructed' '
+	setup_cruft_exclude_tests exclude-cruft-when-instructed &&
+	(
+		cd exclude-cruft-when-instructed &&
+
+		GIT_TEST_MULTI_PACK_INDEX=0 \
+		git -c repack.midxMustContainCruft=true repack \
+			-d --geometric=2 --write-midx --write-bitmap-index &&
+
+		test-tool read-midx --show-objects $objdir >midx &&
+		cruft="$(ls $packdir/*.mtimes)" &&
+		test_grep "$(basename "$cruft" .mtimes).idx" midx &&
+
+		git cat-file --batch-check="%(objectname)" --batch-all-objects \
+			>all.objects &&
+		awk "/\.pack$/ { print \$1 }" <midx | sort >midx.objects &&
+
+		test_cmp all.objects midx.objects
+	)
+'
+
+test_expect_success 'repack --write-midx includes cruft when necessary' '
+	setup_cruft_exclude_tests exclude-cruft-when-necessary &&
+	(
+		cd exclude-cruft-when-necessary &&
+
+		test_path_is_file $(ls $packdir/pack-*.mtimes) &&
+		ls $packdir/pack-*.idx | sort >packs.all &&
+		grep -o "pack-.*\.idx$" packs.all >in &&