diff --git a/Hooks.php b/Hooks.php
index 3e5a54283..f154bcb9c 100644
--- a/Hooks.php
+++ b/Hooks.php
@@ -753,6 +753,8 @@ class EchoHooks {
 			'notifications-alert' => $alertLink,
 		);
 
+		// hasMessages() checks if the user has ever had (local) messages, or if they
+		// have any currently unread message at all (including on foreign wikis)
 		if ( $notifUser->hasMessages() ) {
 			$msgLink = array(
 				'href' => $url,
diff --git a/includes/NotifUser.php b/includes/NotifUser.php
index 047f1bcd7..9a8ac08d4 100644
--- a/includes/NotifUser.php
+++ b/includes/NotifUser.php
@@ -183,7 +183,16 @@ class MWEchoNotifUser {
 	private function getHasMessagesKey() {
 		global $wgEchoConfig;
 
-		return wfMemcKey( 'echo', 'user', 'had', 'messages', $this->mUser->getId(), $wgEchoConfig['version'] );
+		$lookup = CentralIdLookup::factory();
+		$id = $lookup->centralIdFromLocalUser( $this->mUser, CentralIdLookup::AUDIENCE_RAW );
+		if ( !$id ) {
+			// local user
+			return wfMemcKey( 'echo', 'user', 'had', 'messages', $this->mUser->getId(), $wgEchoConfig['version'] );
+		} else {
+			// central user: we don't want a per-wiki cache key: as soon as the user
+			// gets a message on another wiki, this cache key should be altered
+			return wfGlobalCacheKey( 'echo', 'user', 'had', 'messages', $id, $wgEchoConfig['version'] );
+		}
 	}
 
 	/**
@@ -206,13 +215,39 @@ class MWEchoNotifUser {
 		$eventTypesToLoad = $attributeManager->getUserEnabledEventsbySections( $this->mUser, 'web', array( $section ) );
 
 		$count = count( $this->notifMapper->fetchByUser( $this->mUser, 1, 0, $eventTypesToLoad ) );
-
-		$result = (int)( $count > 0 );
+		$result = (int)( $count > 0 ) || $this->hasForeignMessages();
 		$this->cache->set( $memcKey, $result, 86400 );
 
 		return (bool)$result;
 	}
 
+	protected function hasForeignMessages() {
+		if ( !$this->mUser->getOption( 'echo-cross-wiki-notifications' ) ) {
+			return false;
+		}
+
+		$uw = EchoUnreadWikis::newFromUser( $this->mUser );
+		if ( $uw === false ) {
+			return false;
+		}
+
+		$counts = $uw->getUnreadCounts();
+		foreach ( $counts as $wiki => $data ) {
+			if ( $data[EchoAttributeManager::MESSAGE]['count'] > 0 ) {
+				// currently has unread notifications
+				return true;
+			}
+
+			if ( $data[EchoAttributeManager::MESSAGE]['ts'] !== EchoUnreadWikis::DEFAULT_TS ) {
+				// a timestamp at which notifications were read was recorded,
+				// which means the user must've had messages somewhere, at some point
+				return true;
+			}
+		}
+
+		return false;
+	}
+
 	/**
 	 * Cache the fact that the user has messages.
 	 * This is used after the user receives a message, making the system skip the actual test
diff --git a/includes/UnreadWikis.php b/includes/UnreadWikis.php
index 78f7bd3c2..f0243cd0c 100644
--- a/includes/UnreadWikis.php
+++ b/includes/UnreadWikis.php
@@ -2,9 +2,13 @@
 
 /**
  * Manages what wikis a user has unread notifications on
- *
  */
 class EchoUnreadWikis {
+	/**
+	 * @var string
+	 */
+	const DEFAULT_TS = '00000000000000';
+
 	/**
 	 * @var int
 	 */
@@ -48,7 +52,7 @@ class EchoUnreadWikis {
 	}
 
 	/**
-	 * @return array
+	 * @return array Note that also wikis with 0 notifications and/or messages may be included
 	 */
 	public function getUnreadCounts() {
 		$dbr = $this->getDB( DB_SLAVE );
@@ -69,10 +73,6 @@ class EchoUnreadWikis {
 
 		$wikis = array();
 		foreach ( $rows as $row ) {
-			if ( !$row->euw_alerts && !$row->euw_messages ) {
-				// This shouldn't happen, but lets be safe...
-				continue;
-			}
 			$wikis[$row->euw_wiki] = array(
 				EchoAttributeManager::ALERT => array(
 					'count' => $row->euw_alerts,
@@ -101,18 +101,16 @@ class EchoUnreadWikis {
 			return;
 		}
 
-		$defaultTS = '00000000000000';
-
 		if ( $alertCount || $msgCount ) {
 			$values = array(
 				'euw_alerts' => $alertCount,
 				'euw_alerts_ts' => $alertCount
 					? $alertTime->getTimestamp( TS_MW )
-					: $defaultTS,
+					: static::DEFAULT_TS,
 				'euw_messages' => $msgCount,
 				'euw_messages_ts' => $msgCount
 					? $msgTime->getTimestamp( TS_MW )
-					: $defaultTS,
+					: static::DEFAULT_TS,
 			);
 			$dbw->upsert(
 				'echo_unread_wikis',
@@ -125,12 +123,11 @@ class EchoUnreadWikis {
 				__METHOD__
 			);
 		} else {
-			// No unread notifications, delete the row
-			$dbw->delete(
-				'echo_unread_wikis',
-				array( 'euw_user' => $this->id, 'euw_wiki' => $wiki ),
-				__METHOD__
-			);
+			// Even if there are no unread notifications, don't delete the row!
+			// That (empty) row helps us tell the difference between "has had
+			// notifications but all have been seen" (0 count, non-0 timestamp)
+			// and "has never had a notifications before" (row with 0 count and
+			// 000 timestamp or no row at all)
 		}
 	}
 }