diff --git a/src/Content/OEmbed.php b/src/Content/OEmbed.php
index f250889520..55f5e0ad0f 100644
--- a/src/Content/OEmbed.php
+++ b/src/Content/OEmbed.php
@@ -48,11 +48,11 @@ class OEmbed
 	{
 		$embedurl = trim($embedurl, '\'"');
 
-		$a = DI::app();
+		$appHelper = DI::apphelper();
 
-		$cache_key = 'oembed:' . $a->getThemeInfoValue('videowidth') . ':' . $embedurl;
+		$cache_key = 'oembed:' . $appHelper->getThemeInfoValue('videowidth') . ':' . $embedurl;
 
-		$condition = ['url' => Strings::normaliseLink($embedurl), 'maxwidth' => $a->getThemeInfoValue('videowidth')];
+		$condition = ['url' => Strings::normaliseLink($embedurl), 'maxwidth' => $appHelper->getThemeInfoValue('videowidth')];
 		$oembed_record = DBA::selectFirst('oembed', ['content'], $condition);
 		if (DBA::isResult($oembed_record)) {
 			$json_string = $oembed_record['content'];
@@ -88,7 +88,7 @@ class OEmbed
 							// but their OEmbed endpoint is only accessible by HTTPS ¯\_(ツ)_/¯
 							$href = str_replace(['http://www.youtube.com/', 'http://player.vimeo.com/'],
 								['https://www.youtube.com/', 'https://player.vimeo.com/'], $href);
-							$result = DI::httpClient()->get($href . '&maxwidth=' . $a->getThemeInfoValue('videowidth'), HttpClientAccept::DEFAULT, [HttpClientOptions::REQUEST => HttpClientRequest::SITEINFO]);
+							$result = DI::httpClient()->get($href . '&maxwidth=' . $appHelper->getThemeInfoValue('videowidth'), HttpClientAccept::DEFAULT, [HttpClientOptions::REQUEST => HttpClientRequest::SITEINFO]);
 							if ($result->isSuccess()) {
 								$json_string = $result->getBodyString();
 								break;
@@ -109,7 +109,7 @@ class OEmbed
 			if (!empty($oembed->type) && $oembed->type != 'error') {
 				DBA::insert('oembed', [
 					'url' => Strings::normaliseLink($embedurl),
-					'maxwidth' => $a->getThemeInfoValue('videowidth'),
+					'maxwidth' => $appHelper->getThemeInfoValue('videowidth'),
 					'content' => $json_string,
 					'created' => DateTimeFormat::utcNow()
 				], Database::INSERT_UPDATE);
diff --git a/src/Content/Text/BBCode.php b/src/Content/Text/BBCode.php
index b54beef039..9812b7c2bc 100644
--- a/src/Content/Text/BBCode.php
+++ b/src/Content/Text/BBCode.php
@@ -1628,7 +1628,7 @@ class BBCode
 	private static function convertStylesToHtml(string $text, int $simple_html): string
 	{
 		// Markdown is designed to pass through HTML elements that it can't handle itself,
-		// so that the other system would parse the original HTML element. 
+		// so that the other system would parse the original HTML element.
 		// But Diaspora has chosen not to do this and doesn't parse HTML elements.
 		// So we need to make some changes here.
 		if ($simple_html == BBCode::DIASPORA) {
@@ -1924,19 +1924,20 @@ class BBCode
 
 	private static function convertVideoPlatformsToHtml(string $text, bool $try_oembed): string
 	{
-		$a = DI::app();
+		$appHelper = DI::apphelper();
+
 		$text = self::normalizeVideoLinks($text);
 
 		// Youtube extensions
 		if ($try_oembed && OEmbed::isAllowedURL('https://www.youtube.com/embed/')) {
-			$text = preg_replace("/\[youtube\]([A-Za-z0-9\-_=]+)(.*?)\[\/youtube\]/ism", '<iframe width="' . $a->getThemeInfoValue('videowidth') . '" height="' . $a->getThemeInfoValue('videoheight') . '" src="https://www.youtube.com/embed/$1" frameborder="0" ></iframe>', $text);
+			$text = preg_replace("/\[youtube\]([A-Za-z0-9\-_=]+)(.*?)\[\/youtube\]/ism", '<iframe width="' . $appHelper->getThemeInfoValue('videowidth') . '" height="' . $appHelper->getThemeInfoValue('videoheight') . '" src="https://www.youtube.com/embed/$1" frameborder="0" ></iframe>', $text);
 		} else {
 			$text = preg_replace("/\[youtube\]([A-Za-z0-9\-_=]+)(.*?)\[\/youtube\]/ism", '[url]https://www.youtube.com/watch?v=$1[/url]', $text);
 		}
 
 		// Vimeo extensions
 		if ($try_oembed && OEmbed::isAllowedURL('https://player.vimeo.com/video')) {
-			$text = preg_replace("/\[vimeo\]([0-9]+)(.*?)\[\/vimeo\]/ism", '<iframe width="' . $a->getThemeInfoValue('videowidth') . '" height="' . $a->getThemeInfoValue('videoheight') . '" src="https://player.vimeo.com/video/$1" frameborder="0" ></iframe>', $text);
+			$text = preg_replace("/\[vimeo\]([0-9]+)(.*?)\[\/vimeo\]/ism", '<iframe width="' . $appHelper->getThemeInfoValue('videowidth') . '" height="' . $appHelper->getThemeInfoValue('videoheight') . '" src="https://player.vimeo.com/video/$1" frameborder="0" ></iframe>', $text);
 		} else {
 			$text = preg_replace("/\[vimeo\]([0-9]+)(.*?)\[\/vimeo\]/ism", '[url]https://vimeo.com/$1[/url]', $text);
 		}
diff --git a/src/Core/Theme.php b/src/Core/Theme.php
index c6fa572028..81d1016831 100644
--- a/src/Core/Theme.php
+++ b/src/Core/Theme.php
@@ -208,11 +208,11 @@ class Theme
 	 */
 	public static function getPathForFile(string $file): string
 	{
-		$a = DI::app();
+		$appHelper = DI::apphelper();
 
-		$theme = $a->getCurrentTheme();
+		$theme = $appHelper->getCurrentTheme();
 
-		$parent = Strings::sanitizeFilePathItem($a->getThemeInfoValue('extends', $theme));
+		$parent = Strings::sanitizeFilePathItem($appHelper->getThemeInfoValue('extends', $theme));
 
 		$paths = [
 			"view/theme/$theme/$file",
@@ -245,11 +245,11 @@ class Theme
 			return 'view/theme/' . $theme . '/style.css';
 		}
 
-		$a = DI::app();
+		$appHelper = DI::apphelper();
 
 		$query_params = [];
 
-		$puid = Profile::getThemeUid($a);
+		$puid = Profile::getThemeUid($appHelper);
 		if ($puid) {
 			$query_params['puid'] = $puid;
 		}
@@ -267,8 +267,8 @@ class Theme
 	{
 		$theme = Strings::sanitizeFilePathItem($theme);
 
-		$a = DI::app();
-		$base_theme = $a->getThemeInfoValue('extends') ?? '';
+		$appHelper = DI::apphelper();
+		$base_theme = $appHelper->getThemeInfoValue('extends') ?? '';
 
 		if (file_exists("view/theme/$theme/config.php")) {
 			return "view/theme/$theme/config.php";
diff --git a/src/Model/Item.php b/src/Model/Item.php
index 0a000f8c1e..cbd0d0f705 100644
--- a/src/Model/Item.php
+++ b/src/Model/Item.php
@@ -3347,7 +3347,7 @@ class Item
 	 */
 	public static function prepareBody(array &$item, bool $attach = false, bool $is_preview = false, bool $only_cache = false): string
 	{
-		$a = DI::app();
+		$appHelper = DI::apphelper();
 		$uid = DI::userSession()->getLocalUserId();
 		Hook::callAll('prepare_body_init', $item);
 
@@ -3517,8 +3517,8 @@ class Item
 		}
 
 		// Replace friendica image url size with theme preference.
-		if (!empty($a->getThemeInfoValue('item_image_size'))) {
-			$ps = $a->getThemeInfoValue('item_image_size');
+		if (!empty($appHelper->getThemeInfoValue('item_image_size'))) {
+			$ps = $appHelper->getThemeInfoValue('item_image_size');
 			$s = preg_replace('|(<img[^>]+src="[^"]+/photo/[0-9a-f]+)-[0-9]|', "$1-" . $ps, $s);
 		}