diff --git a/src/QuickInstall/Sandbox/SeedRuntime/ContentBuilder.php b/src/QuickInstall/Sandbox/SeedRuntime/ContentBuilder.php
index eb15e471..b6fd62f9 100644
--- a/src/QuickInstall/Sandbox/SeedRuntime/ContentBuilder.php
+++ b/src/QuickInstall/Sandbox/SeedRuntime/ContentBuilder.php
@@ -477,9 +477,8 @@ private function createReply(
 	private function postData(int $forumId, int $topicId, string $subject, string $message): array
 	{
 		$db = $this->context->db;
-		$uid = $bitfield = '';
-		$options = 7;
-		generate_text_for_storage($message, $uid, $bitfield, $options, true, true, true);
+		$parser = $this->parseMessage($message);
+		$message = $parser->message;
 		$result = $db->sql_query_limit('SELECT forum_name FROM ' . FORUMS_TABLE . ' WHERE forum_id = ' . $forumId, 1);
 		$forumName = (string) $db->sql_fetchfield('forum_name');
 		$db->sql_freeresult($result);
@@ -497,8 +496,8 @@ private function postData(int $forumId, int $topicId, string $subject, string $m
 			'enable_sig' => true,
 			'message' => $message,
 			'message_md5' => md5($message),
-			'bbcode_bitfield' => $bitfield,
-			'bbcode_uid' => $uid,
+			'bbcode_bitfield' => $parser->bbcode_bitfield,
+			'bbcode_uid' => $parser->bbcode_uid,
 			'post_edit_locked' => 0,
 			'notify_set' => false,
 			'notify' => false,
diff --git a/src/QuickInstall/Sandbox/SeedRuntime/SeedContext.php b/src/QuickInstall/Sandbox/SeedRuntime/SeedContext.php
index 7ec13f02..e9af2638 100644
--- a/src/QuickInstall/Sandbox/SeedRuntime/SeedContext.php
+++ b/src/QuickInstall/Sandbox/SeedRuntime/SeedContext.php
@@ -415,6 +415,20 @@ public function __construct(SeedContext $context)
 		$this->context = $context;
 	}
 
+	/** Parses user-authored content through phpBB's posting pipeline. */
+	protected function parseMessage(string $message)
+	{
+		$parser = new \parse_message($message);
+		// Keep phpBB's generated UID even with TextFormatter's empty legacy bitfield.
+		$parser->parse(true, true, true, true, true, true, true);
+		if ($parser->warn_msg)
+		{
+			throw new RuntimeException('Unable to parse seed message: ' . implode(' ', $parser->warn_msg));
+		}
+
+		return $parser;
+	}
+
 	/** Returns the last inserted ID across supported phpBB DBAL versions. */
 	protected function lastInsertedId(): int
 	{
diff --git a/src/QuickInstall/Sandbox/SeedRuntime/StateBuilder.php b/src/QuickInstall/Sandbox/SeedRuntime/StateBuilder.php
index 62ecfe19..4d6347d9 100644
--- a/src/QuickInstall/Sandbox/SeedRuntime/StateBuilder.php
+++ b/src/QuickInstall/Sandbox/SeedRuntime/StateBuilder.php
@@ -207,9 +207,7 @@ private function sendMessage(int $recipientId, string $label, string $message):
 		$db->sql_freeresult($result);
 		if (!$messageId)
 		{
-			$uid = $bitfield = '';
-			$options = 7;
-			generate_text_for_storage($message, $uid, $bitfield, $options, true, true, true);
+			$parser = $this->parseMessage($message);
 			$data = [
 				'address_list' => ['u' => [$recipientId => 'to']],
 				'from_user_id' => $authorId,
@@ -220,9 +218,9 @@ private function sendMessage(int $recipientId, string $label, string $message):
 				'enable_smilies' => true,
 				'enable_urls' => true,
 				'icon_id' => 0,
-				'bbcode_uid' => $uid,
-				'bbcode_bitfield' => $bitfield,
-				'message' => $message,
+				'bbcode_uid' => $parser->bbcode_uid,
+				'bbcode_bitfield' => $parser->bbcode_bitfield,
+				'message' => $parser->message,
 			];
 			submit_pm('post', $subject, $data, true);
 			$messageId = (int) ($data['msg_id'] ?? 0);
diff --git a/src/QuickInstall/Sandbox/SeedRuntime/run.php b/src/QuickInstall/Sandbox/SeedRuntime/run.php
index a9354b02..68e7c4af 100644
--- a/src/QuickInstall/Sandbox/SeedRuntime/run.php
+++ b/src/QuickInstall/Sandbox/SeedRuntime/run.php
@@ -63,6 +63,7 @@
 
 require_once $phpbb_root_path . 'includes/functions_user.' . $phpEx;
 require_once $phpbb_root_path . 'includes/functions_content.' . $phpEx;
+require_once $phpbb_root_path . 'includes/message_parser.' . $phpEx;
 require_once $phpbb_root_path . 'includes/functions_posting.' . $phpEx;
 require_once $phpbb_root_path . 'includes/functions_admin.' . $phpEx;
 require_once $phpbb_root_path . 'includes/functions_privmsgs.' . $phpEx;
diff --git a/tests/Unit/SeederPackageTest.php b/tests/Unit/SeederPackageTest.php
index 3a43d713..bbee6f80 100644
--- a/tests/Unit/SeederPackageTest.php
+++ b/tests/Unit/SeederPackageTest.php
@@ -40,6 +40,7 @@ public function testWritesUnifiedSeederPackage(): void
 		$run = file_get_contents($path . '/run.php');
 		self::assertStringContainsString("getenv('QUICKINSTALL_SEED_RUNTIME') !== '1'", $run);
 		self::assertStringContainsString('!isset($argv[1], $argv[2], $argv[3])', $run);
+		self::assertStringContainsString("'includes/message_parser.'", $run);
 		self::assertFileDoesNotExist($path . '/StandardSeeder.php');
 		self::assertStringContainsString("'25 users'", file_get_contents($path . '/DevelopmentSeeder.php'));
 		self::assertStringContainsString("'90 posts'", file_get_contents($path . '/DevelopmentSeeder.php'));
@@ -61,6 +62,11 @@ public function testWritesUnifiedSeederPackage(): void
 		self::assertStringContainsString("ids('logs')", file_get_contents($path . '/Seeder.php'));
 		self::assertStringContainsString('[size=50]Smaller text[/size]', file_get_contents($path . '/ContentBuilder.php'));
 		self::assertStringContainsString('[list=a]', file_get_contents($path . '/ContentBuilder.php'));
+		self::assertStringContainsString('new \\parse_message($message)', file_get_contents($path . '/SeedContext.php'));
+		self::assertStringContainsString('$this->parseMessage($message)', file_get_contents($path . '/ContentBuilder.php'));
+		self::assertStringContainsString('$this->parseMessage($message)', file_get_contents($path . '/StateBuilder.php'));
+		self::assertStringContainsString("'bbcode_uid' => \$parser->bbcode_uid", file_get_contents($path . '/ContentBuilder.php'));
+		self::assertStringContainsString("'bbcode_uid' => \$parser->bbcode_uid", file_get_contents($path . '/StateBuilder.php'));
 		self::assertStringContainsString('reply with three quote levels', file_get_contents($path . '/ContentBuilder.php'));
 		self::assertStringContainsString('SupercalifragilisticexpialidociousSupercalifragilisticexpialidocious', file_get_contents($path . '/ContentBuilder.php'));
 		self::assertStringContainsString('Unread private message', file_get_contents($path . '/StateBuilder.php'));