diff --git a/src/Model/APContact.php b/src/Model/APContact.php
index 3b568f39f1..67ce2b66bf 100644
--- a/src/Model/APContact.php
+++ b/src/Model/APContact.php
@@ -305,8 +305,8 @@ class APContact
 
 		$apcontact['pubkey'] = null;
 		if (!empty($compacted['w3id:publicKey'])) {
-			$apcontact['pubkey'] = trim(JsonLD::fetchElement($compacted['w3id:publicKey'], 'w3id:publicKeyPem', '@value'));
-			if (strstr($apcontact['pubkey'], 'RSA ')) {
+			$apcontact['pubkey'] = trim(JsonLD::fetchElement($compacted['w3id:publicKey'], 'w3id:publicKeyPem', '@value') ?? '');
+			if (strpos($apcontact['pubkey'], 'RSA ') !== false) {
 				$apcontact['pubkey'] = Crypto::rsaToPem($apcontact['pubkey']);
 			}
 		}
diff --git a/src/Navigation/Notifications/ValueObject/Introduction.php b/src/Navigation/Notifications/ValueObject/Introduction.php
index cb27b38886..da664ce8e5 100644
--- a/src/Navigation/Notifications/ValueObject/Introduction.php
+++ b/src/Navigation/Notifications/ValueObject/Introduction.php
@@ -226,6 +226,7 @@ class Introduction implements \JsonSerializable
 	/**
 	 * @inheritDoc
 	 */
+	#[\ReturnTypeWillChange]
 	public function jsonSerialize()
 	{
 		return $this->toArray();
diff --git a/src/Protocol/DFRN.php b/src/Protocol/DFRN.php
index da4db5d9ad..a86cf2094d 100644
--- a/src/Protocol/DFRN.php
+++ b/src/Protocol/DFRN.php
@@ -538,7 +538,7 @@ class DFRN
 
 			XML::addElement($doc, $author, 'poco:utcOffset', DateTimeFormat::timezoneNow($profile['timezone'], 'P'));
 
-			if (trim($profile['homepage']) != '') {
+			if (trim($profile['homepage'])) {
 				$urls = $doc->createElement('poco:urls');
 				XML::addElement($doc, $urls, 'poco:type', 'homepage');
 				XML::addElement($doc, $urls, 'poco:value', $profile['homepage']);
@@ -546,7 +546,7 @@ class DFRN
 				$author->appendChild($urls);
 			}
 
-			if (trim($profile['pub_keywords']) != '') {
+			if (trim($profile['pub_keywords'] ?? '')) {
 				$keywords = explode(',', $profile['pub_keywords']);
 
 				foreach ($keywords as $keyword) {
@@ -554,7 +554,7 @@ class DFRN
 				}
 			}
 
-			if (trim($profile['xmpp']) != '') {
+			if (trim($profile['xmpp'])) {
 				$ims = $doc->createElement('poco:ims');
 				XML::addElement($doc, $ims, 'poco:type', 'xmpp');
 				XML::addElement($doc, $ims, 'poco:value', $profile['xmpp']);
@@ -562,7 +562,7 @@ class DFRN
 				$author->appendChild($ims);
 			}
 
-			if (trim($profile['locality'] . $profile['region'] . $profile['country-name']) != '') {
+			if (trim($profile['locality'] . $profile['region'] . $profile['country-name'])) {
 				$element = $doc->createElement('poco:address');
 
 				XML::addElement($doc, $element, 'poco:formatted', Profile::formatLocation($profile));