diff --git a/git.c b/git.c
index 18bed9a996..60c2784be4 100644
--- a/git.c
+++ b/git.c
@@ -561,7 +561,7 @@ static struct cmd_struct commands[] = {
 	{ "merge-tree", cmd_merge_tree, RUN_SETUP | NO_PARSEOPT },
 	{ "mktag", cmd_mktag, RUN_SETUP | NO_PARSEOPT },
 	{ "mktree", cmd_mktree, RUN_SETUP },
-	{ "multi-pack-index", cmd_multi_pack_index, RUN_SETUP_GENTLY },
+	{ "multi-pack-index", cmd_multi_pack_index, RUN_SETUP },
 	{ "mv", cmd_mv, RUN_SETUP | NEED_WORK_TREE },
 	{ "name-rev", cmd_name_rev, RUN_SETUP },
 	{ "notes", cmd_notes, RUN_SETUP },
diff --git a/t/t5319-multi-pack-index.sh b/t/t5319-multi-pack-index.sh
index 3d4d9f10c3..9034e94c0a 100755
--- a/t/t5319-multi-pack-index.sh
+++ b/t/t5319-multi-pack-index.sh
@@ -842,4 +842,9 @@ test_expect_success 'usage shown without sub-command' '
 	! test_i18ngrep "unrecognized subcommand" err
 '
 
+test_expect_success 'complains when run outside of a repository' '
+	nongit test_must_fail git multi-pack-index write 2>err &&
+	grep "not a git repository" err
+'
+
 test_done