diff --git a/phpBB/phpbb/db/migration/data/v400/hidpi_smilies.php b/phpBB/phpbb/db/migration/data/v400/hidpi_smilies.php
new file mode 100644
index 0000000000..60f65b5f14
--- /dev/null
+++ b/phpBB/phpbb/db/migration/data/v400/hidpi_smilies.php
@@ -0,0 +1,89 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\db\migration\data\v400;
+
+use phpbb\db\migration\migration;
+
+class hidpi_smilies extends migration
+{
+	private array $default_smilies = [
+		'icon_arrow',
+		'icon_cool',
+		'icon_cry',
+		'icon_e_biggrin',
+		'icon_e_confused',
+		'icon_e_geek',
+		'icon_e_sad',
+		'icon_e_smile',
+		'icon_e_surprised',
+		'icon_e_ugeek',
+		'icon_e_wink',
+		'icon_eek',
+		'icon_evil',
+		'icon_exclaim',
+		'icon_idea',
+		'icon_lol',
+		'icon_mad',
+		'icon_mrgreen',
+		'icon_neutral',
+		'icon_question',
+		'icon_razz',
+		'icon_redface',
+		'icon_rolleyes',
+		'icon_twisted',
+	];
+
+	public static function depends_on(): array
+	{
+		return [
+			'\phpbb\db\migration\data\v400\dev'
+		];
+	}
+
+	public function update_data(): array
+	{
+		return [
+			['custom', [[$this, 'gif_to_svg_smilies']]],
+		];
+	}
+
+	public function revert_data(): array
+	{
+		return [
+			['custom', [[$this, 'svg_to_gif_smilies']]],
+		];
+	}
+
+	public function gif_to_svg_smilies(): void
+	{
+		foreach ($this->default_smilies as $smiley)
+		{
+			$sql = 'UPDATE ' . $this->tables['smilies'] . "smilies
+				SET smiley_url = '" . $this->db->sql_escape($smiley) . ".svg'
+				WHERE smiley_url = '" . $this->db->sql_escape($smiley) . ".gif'";
+			$this->db->sql_query($sql);
+		}
+	}
+
+	public function svg_to_gif_smilies(): void
+	{
+		foreach ($this->default_smilies as $smiley)
+		{
+			$sql = 'UPDATE ' . $this->tables['smilies'] . "
+				SET smiley_url = '" . $this->db->sql_escape($smiley) . ".gif'
+				WHERE smiley_url = '" . $this->db->sql_escape($smiley) . ".svg'";
+			$this->db->sql_query($sql);
+		}
+	}
+}