diff --git a/apps/dav/lib/Connector/PublicAuth.php b/apps/dav/lib/Connector/PublicAuth.php
index 74d65c1669f0e..55d2de72228ee 100644
--- a/apps/dav/lib/Connector/PublicAuth.php
+++ b/apps/dav/lib/Connector/PublicAuth.php
@@ -109,7 +109,7 @@ protected function validateUserPass($username, $password) {
 					if (in_array('XMLHttpRequest', explode(',', $this->request->getHeader('X-Requested-With')))) {
 						// do not re-authenticate over ajax, use dummy auth name to prevent browser popup
 						http_response_code(401);
-						header('WWW-Authenticate','DummyBasic realm="' . $this->realm . '"');
+						header('WWW-Authenticate: DummyBasic realm="' . $this->realm . '"');
 						throw new \Sabre\DAV\Exception\NotAuthenticated('Cannot authenticate over ajax calls');
 					}
 					return false;