diff --git a/apps/dav/lib/CalDAV/CalDavBackend.php b/apps/dav/lib/CalDAV/CalDavBackend.php
index fcf73cb0f3..ef3df8de83 100644
--- a/apps/dav/lib/CalDAV/CalDavBackend.php
+++ b/apps/dav/lib/CalDAV/CalDavBackend.php
@@ -2009,7 +2009,7 @@ class CalDavBackend extends AbstractBackend implements SyncSupport, Subscription
 				if (in_array($property->name, self::$indexProperties)) {
 					$value = $property->getValue();
 					// is this a shitty db?
-					if ($this->db->supports4ByteText()) {
+					if (!$this->db->supports4ByteText()) {
 						$value = preg_replace('/[\x{10000}-\x{10FFFF}]/u', "\xEF\xBF\xBD", $value);
 					}
 					$value = substr($value, 0, 254);
diff --git a/apps/dav/tests/unit/CalDAV/CalDavBackendTest.php b/apps/dav/tests/unit/CalDAV/CalDavBackendTest.php
index dc531b5a64..fa298282d7 100644
--- a/apps/dav/tests/unit/CalDAV/CalDavBackendTest.php
+++ b/apps/dav/tests/unit/CalDAV/CalDavBackendTest.php
@@ -539,7 +539,7 @@ CREATED;VALUE=DATE-TIME:20130910T125139Z
 UID:47d15e3ec8
 LAST-MODIFIED;VALUE=DATE-TIME:20130910T125139Z
 DTSTAMP;VALUE=DATE-TIME:20130910T125139Z
-SUMMARY:123 Event
+SUMMARY:123 Event 🙈
 DTSTART;VALUE=DATE-TIME:20130912T130000Z
 DTEND;VALUE=DATE-TIME:20130912T140000Z
 ATTENDEE;CN=test:mailto:foo@bar.com