diff --git a/revision.c b/revision.c
index 78397d6486..71e62d8312 100644
--- a/revision.c
+++ b/revision.c
@@ -709,7 +709,7 @@ static int still_interesting(struct commit_list *src, unsigned long date, int sl
 	 * Does the destination list contain entries with a date
 	 * before the source list? Definitely _not_ done.
 	 */
-	if (date < src->item->date)
+	if (date <= src->item->date)
 		return SLOP;
 
 	/*
diff --git a/t/t6009-rev-list-parent.sh b/t/t6009-rev-list-parent.sh
index 30507407ff..66cda17ef3 100755
--- a/t/t6009-rev-list-parent.sh
+++ b/t/t6009-rev-list-parent.sh
@@ -133,4 +133,17 @@ test_expect_success 'dodecapus' '
 	check_revlist "--min-parents=13" &&
 	check_revlist "--min-parents=4 --max-parents=11" tetrapus
 '
+
+test_expect_success 'ancestors with the same commit time' '
+
+	test_tick_keep=$test_tick &&
+	for i in 1 2 3 4 5 6 7 8; do
+		test_tick=$test_tick_keep
+		test_commit t$i
+	done &&
+	git rev-list t1^! --not t$i >result &&
+	>expect &&
+	test_cmp expect result
+'
+
 test_done