diff --git a/revision.c b/revision.c
index 33cb207f28..3536635a88 100644
--- a/revision.c
+++ b/revision.c
@@ -1424,6 +1424,22 @@ static struct merge_simplify_state *locate_simplify_state(struct rev_info *revs,
 	return st;
 }
 
+static void remove_treesame_parents(struct commit *commit)
+{
+	struct commit_list **pp, *p;
+
+	pp = &commit->parents;
+	while ((p = *pp) != NULL) {
+		struct commit *parent = p->item;
+		if (parent->object.flags & TREESAME) {
+			*pp = p->next;
+			free(p);
+			continue;
+		}
+		pp = &p->next;
+	}
+}
+
 static struct commit_list **simplify_one(struct rev_info *revs, struct commit *commit, struct commit_list **tail)
 {
 	struct commit_list *p;
@@ -1469,6 +1485,13 @@ static struct commit_list **simplify_one(struct rev_info *revs, struct commit *c
 		pst = locate_simplify_state(revs, p->item);
 		p->item = pst->simplified;
 	}
+
+	/*
+	 * A merge with a tree-same parent is useless
+	 */
+	if (commit->parents && commit->parents->next)
+		remove_treesame_parents(commit);
+
 	cnt = remove_duplicate_parents(commit);
 
 	/*
diff --git a/t/t6012-rev-list-simplify.sh b/t/t6012-rev-list-simplify.sh
index 510bb9679f..d6d79c467f 100755
--- a/t/t6012-rev-list-simplify.sh
+++ b/t/t6012-rev-list-simplify.sh
@@ -59,7 +59,23 @@ test_expect_success setup '
 
 	echo "Final change" >file &&
 	test_tick && git commit -a -m "Final change" &&
-	note I
+	note I &&
+
+	git symbolic-ref HEAD refs/heads/unrelated &&
+	git rm -f "*" &&
+	echo "Unrelated branch" >side &&
+	git add side &&
+	test_tick && git commit -m "Side root" &&
+	note J &&
+
+	git checkout master &&
+	test_tick && git merge -m "Coolest" unrelated &&
+	note K &&
+
+	echo "Immaterial" >elif &&
+	git add elif &&
+	test_tick && git commit -m "Last" &&
+	note L
 '
 
 FMT='tformat:%P 	%H | %s'
@@ -82,10 +98,10 @@ check_result () {
 	'
 }
 
-check_result 'I H G F E D C B A' --full-history
-check_result 'I H E C B A' --full-history -- file
-check_result 'I H E C B A' --full-history --topo-order -- file
-check_result 'I H E C B A' --full-history --date-order -- file
+check_result 'L K J I H G F E D C B A' --full-history
+check_result 'K I H E C B A' --full-history -- file
+check_result 'K I H E C B A' --full-history --topo-order -- file
+check_result 'K I H E C B A' --full-history --date-order -- file
 check_result 'I E C B A' --simplify-merges -- file
 check_result 'I B A' -- file
 check_result 'I B A' --topo-order -- file