diff --git a/sequencer.c b/sequencer.c
index 287f4e5e876632..459066e43baa73 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -1941,10 +1941,10 @@ static int seen_squash(struct replay_ctx *ctx)
 
 static void update_comment_bufs(struct strbuf *buf1, struct strbuf *buf2, int n)
 {
-	strbuf_setlen(buf1, 2);
+	strbuf_setlen(buf1, strlen(comment_line_str) + 1);
 	strbuf_addf(buf1, _(nth_commit_msg_fmt), n);
 	strbuf_addch(buf1, '\n');
-	strbuf_setlen(buf2, 2);
+	strbuf_setlen(buf2, strlen(comment_line_str) + 1);
 	strbuf_addf(buf2, _(skip_nth_commit_msg_fmt), n);
 	strbuf_addch(buf2, '\n');
 }
@@ -1963,8 +1963,12 @@ static void update_squash_message_for_fixup(struct strbuf *msg)
 	size_t orig_msg_len;
 	int i = 1;
 
-	strbuf_addf(&buf1, "# %s\n", _(first_commit_msg_str));
-	strbuf_addf(&buf2, "# %s\n", _(skip_first_commit_msg_str));
+	strbuf_add_commented_lines(&buf1, _(first_commit_msg_str),
+				   strlen(_(first_commit_msg_str)),
+				   comment_line_str);
+	strbuf_add_commented_lines(&buf2, _(skip_first_commit_msg_str),
+				   strlen(_(skip_first_commit_msg_str)),
+				   comment_line_str);
 	s = start = orig_msg = strbuf_detach(msg, &orig_msg_len);
 	while (s) {
 		const char *next;
@@ -2341,8 +2345,8 @@ static int do_pick_commit(struct repository *r,
 		next = parent;
 		next_label = msg.parent_label;
 		if (opts->commit_use_reference) {
-			strbuf_addstr(&ctx->message,
-				"# *** SAY WHY WE ARE REVERTING ON THE TITLE LINE ***");
+			strbuf_commented_addf(&ctx->message, comment_line_str,
+				"*** SAY WHY WE ARE REVERTING ON THE TITLE LINE ***");
 		} else if (skip_prefix(msg.subject, "Revert \"", &orig_subject) &&
 			   /*
 			    * We don't touch pre-existing repeated reverts, because
@@ -2352,12 +2356,13 @@ static int do_pick_commit(struct repository *r,
 			   !starts_with(orig_subject, "Revert \"")) {
 			strbuf_addstr(&ctx->message, "Reapply \"");
 			strbuf_addstr(&ctx->message, orig_subject);
+			strbuf_addstr(&ctx->message, "\n");
 		} else {
 			strbuf_addstr(&ctx->message, "Revert \"");
 			strbuf_addstr(&ctx->message, msg.subject);
-			strbuf_addstr(&ctx->message, "\"");
+			strbuf_addstr(&ctx->message, "\"\n");
 		}
-		strbuf_addstr(&ctx->message, "\n\nThis reverts commit ");
+		strbuf_addstr(&ctx->message, "\nThis reverts commit ");
 		refer_to_commit(opts, &ctx->message, commit);
 
 		if (commit->parents && commit->parents->next) {
@@ -6382,8 +6387,9 @@ static int add_decorations_to_list(const struct commit *commit,
 		/* If the branch is checked out, then leave a comment instead. */
 		if ((path = branch_checked_out(decoration->name))) {
 			item->command = TODO_COMMENT;
-			strbuf_addf(ctx->buf, "# Ref %s checked out at '%s'\n",
-				    decoration->name, path);
+			strbuf_commented_addf(ctx->buf, comment_line_str,
+					      "Ref %s checked out at '%s'\n",
+					      decoration->name, path);
 		} else {
 			struct string_list_item *sti;
 			item->command = TODO_UPDATE_REF;
diff --git a/t/t3400-rebase.sh b/t/t3400-rebase.sh
index bab675938a3e06..c0c00fbb7b1e4e 100755
--- a/t/t3400-rebase.sh
+++ b/t/t3400-rebase.sh
@@ -455,4 +455,23 @@ test_expect_success 'rebase when inside worktree subdirectory' '
 	)
 '
 
+test_expect_success 'git rebase --update-ref with core.commentChar and branch on worktree' '
+	test_when_finished git branch -D base topic2 &&
+	test_when_finished git checkout main &&
+	test_when_finished git branch -D wt-topic &&
+	test_when_finished git worktree remove wt-topic &&
+	git checkout main &&
+	git checkout -b base &&
+	git checkout -b topic2 &&
+	test_commit msg2 &&
+	git worktree add wt-topic &&
+	git checkout base &&
+	test_commit msg3 &&
+	git checkout topic2 &&
+	GIT_SEQUENCE_EDITOR="cat >actual" git -c core.commentChar=% \
+		 rebase -i --update-refs base &&
+	test_grep "% Ref refs/heads/wt-topic checked out at" actual &&
+	test_grep "% Ref refs/heads/topic2 checked out at" actual
+'
+
 test_done
diff --git a/t/t3437-rebase-fixup-options.sh b/t/t3437-rebase-fixup-options.sh
index 6f9307e0e3cdfe..5d306a476928b1 100755
--- a/t/t3437-rebase-fixup-options.sh
+++ b/t/t3437-rebase-fixup-options.sh
@@ -126,6 +126,21 @@ test_expect_success 'fixup -C with conflicts gives correct message' '
 	test_cmp expected-author actual-author
 '
 
+test_expect_success 'conflicting fixup -C after fixup with custom comment string' '
+	test_config core.commentString COMMENT &&
+	test_when_finished "test_might_fail git rebase --abort" &&
+	git checkout --detach A3 &&
+	test_must_fail env FAKE_LINES="1 fixup 2 fixup_-C 4" git rebase -i A &&
+	echo resolved >A &&
+	git add A &&
+	FAKE_COMMIT_AMEND=edited git rebase --continue &&
+	test_commit_message HEAD <<-\EOF
+	A3
+
+	edited
+	EOF
+'
+
 test_expect_success 'skipping fixup -C after fixup gives correct message' '
 	test_when_finished "test_might_fail git rebase --abort" &&
 	git checkout --detach A3 &&
diff --git a/t/t3501-revert-cherry-pick.sh b/t/t3501-revert-cherry-pick.sh
index 17a99379625450..9e8c51b4e2e9f4 100755
--- a/t/t3501-revert-cherry-pick.sh
+++ b/t/t3501-revert-cherry-pick.sh
@@ -227,6 +227,20 @@ test_expect_success 'identification of reverted commit (--reference)' '
 	test_cmp expect actual
 '
 
+test_expect_success 'git revert --reference with core.commentChar' '
+	test_when_finished "git reset --hard to-ident" &&
+	git checkout --detach to-ident &&
+	GIT_EDITOR="head -n4 >actual" git -c core.commentChar=% revert \
+		--edit --reference HEAD &&
+	cat <<-EOF >expect &&
+	% *** SAY WHY WE ARE REVERTING ON THE TITLE LINE ***
+
+	This reverts commit $(git show -s --pretty=reference HEAD^).
+
+	EOF
+	test_cmp expect actual
+'
+
 test_expect_success 'identification of reverted commit (revert.reference)' '
 	git checkout --detach to-ident &&
 	git -c revert.reference=true revert --no-edit HEAD &&