diff --git a/includes/SubscriptionStore.php b/includes/SubscriptionStore.php
index 86f007fce..19175ef7e 100644
--- a/includes/SubscriptionStore.php
+++ b/includes/SubscriptionStore.php
@@ -214,6 +214,13 @@ class SubscriptionStore {
 		if ( !$user->isRegistered() || $this->userIdentityUtils->isTemp( $user ) ) {
 			return false;
 		}
+
+		$section = $target->getFragment();
+		// Truncate to the database field length, taking care not to mess up multibyte characters,
+		// appending a marker so that we can recognize this happened and display an ellipsis later.
+		// Using U+001F "Unit Separator" seems appropriate, and it can't occur in wikitext.
+		$truncSection = strlen( $section ) > 254 ? mb_strcut( $section, 0, 254 ) . "\x1f" : $section;
+
 		$dbw = $this->dbProvider->getPrimaryDatabase();
 		$dbw->upsert(
 			'discussiontools_subscription',
@@ -221,7 +228,7 @@ class SubscriptionStore {
 				'sub_user' => $user->getId(),
 				'sub_namespace' => $target->getNamespace(),
 				'sub_title' => $target->getDBkey(),
-				'sub_section' => $target->getFragment(),
+				'sub_section' => $truncSection,
 				'sub_item' => $itemName,
 				'sub_state' => $state,
 				'sub_created' => $dbw->timestamp(),
diff --git a/includes/TopicSubscriptionsPager.php b/includes/TopicSubscriptionsPager.php
index 3ca767b70..932fbe6f7 100644
--- a/includes/TopicSubscriptionsPager.php
+++ b/includes/TopicSubscriptionsPager.php
@@ -80,12 +80,21 @@ class TopicSubscriptionsPager extends TablePager {
 						$this->msg( 'discussiontools-topicsubscription-pager-newtopics-label' )->escaped() .
 					'</em>';
 				} else {
-					$titleSection = Title::makeTitleSafe( $row->sub_namespace, $row->sub_title, $row->sub_section );
-					if ( !$titleSection ) {
-						// Handle invalid titles (T345648)
-						return htmlspecialchars( $row->sub_section );
+					$section = $row->sub_section;
+					// Detect truncated section titles: either intentionally truncated by SubscriptionStore,
+					// or incorrect multibyte truncation of old entries (T345648).
+					$last = mb_substr( $section, -1 );
+					if ( $last !== '' && ( $last === "\x1f" || mb_ord( $last ) === false ) ) {
+						$section = substr( $section, 0, -strlen( $last ) );
+						// We can't link to the section correctly, since the only link we have is truncated
+						return htmlspecialchars( $section ) . $this->msg( 'ellipsis' )->escaped();
 					}
-					return $linkRenderer->makeLink( $titleSection, $row->sub_section );
+					$titleSection = Title::makeTitleSafe( $row->sub_namespace, $row->sub_title, $section );
+					if ( !$titleSection ) {
+						// Handle invalid titles of any other kind, just in case
+						return htmlspecialchars( $section );
+					}
+					return $linkRenderer->makeLink( $titleSection, $section );
 				}
 
 			case '_page':