diff --git a/lib/DigestSender.php b/lib/DigestSender.php
index 0dfe4d380..5acbdb86b 100644
--- a/lib/DigestSender.php
+++ b/lib/DigestSender.php
@@ -235,7 +235,7 @@ protected function getHTMLSubject(IEvent $event): string {
 			}
 
 			if (isset($parameter['link'])) {
-				$replacements[] = '<a href="' . $parameter['link'] . '">' . htmlspecialchars($replacement) . '</a>';
+				$replacements[] = '<a href="' . htmlspecialchars((string)$parameter['link'], ENT_QUOTES) . '">' . htmlspecialchars($replacement) . '</a>';
 			} else {
 				$replacements[] = '<strong>' . htmlspecialchars($replacement) . '</strong>';
 			}
diff --git a/lib/MailQueueHandler.php b/lib/MailQueueHandler.php
index ee68dba79..d130af69f 100644
--- a/lib/MailQueueHandler.php
+++ b/lib/MailQueueHandler.php
@@ -393,7 +393,7 @@ protected function getHTMLSubject(IEvent $event): string {
 			}
 
 			if (isset($parameter['link'])) {
-				$replacements[] = '<a href="' . $parameter['link'] . '">' . htmlspecialchars($replacement) . '</a>';
+				$replacements[] = '<a href="' . htmlspecialchars((string)$parameter['link'], ENT_QUOTES) . '">' . htmlspecialchars($replacement) . '</a>';
 			} else {
 				$replacements[] = '<strong>' . htmlspecialchars($replacement) . '</strong>';
 			}