diff --git a/apps/dav/lib/CardDAV/CardDavBackend.php b/apps/dav/lib/CardDAV/CardDavBackend.php
index 90ab40c6d1b398f3868ae43f15eea5ffc7d0dd66..51d24351c05b37e6b014a85e4691486c1fdc8add 100644
--- a/apps/dav/lib/CardDAV/CardDavBackend.php
+++ b/apps/dav/lib/CardDAV/CardDavBackend.php
@@ -82,7 +82,8 @@ class CardDavBackend implements BackendInterface, SyncSupport {
 	/** @var array properties to index */
 	public static $indexProperties = [
 		'BDAY', 'UID', 'N', 'FN', 'TITLE', 'ROLE', 'NOTE', 'NICKNAME',
-		'ORG', 'CATEGORIES', 'EMAIL', 'TEL', 'IMPP', 'ADR', 'URL', 'GEO', 'CLOUD'];
+		'ORG', 'CATEGORIES', 'EMAIL', 'TEL', 'IMPP', 'ADR', 'URL', 'GEO',
+		'CLOUD', 'X-SOCIALPROFILE'];
 
 	/**
 	 * @var string[] Map of uid => display name