diff --git a/lib/private/Collaboration/Collaborators/LookupPlugin.php b/lib/private/Collaboration/Collaborators/LookupPlugin.php
index b83235a35e17c..4dd738df327cb 100644
--- a/lib/private/Collaboration/Collaborators/LookupPlugin.php
+++ b/lib/private/Collaboration/Collaborators/LookupPlugin.php
@@ -52,11 +52,16 @@ public function search($search, $limit, $offset, ISearchResult $searchResult): b
 
 		try {
 			$client = $this->clientService->newClient();
+			/**
+			 * @psalm-suppress TypeDoesNotContainType - $isGlobalScaleEnabled always true at this point
+			 * @psalm-suppress RedundantCondition - guard rail in case we re-activate LUS out of GlobalScale
+			 */
 			$response = $client->get(
 				$lookupServerUrl . '/users?search=' . urlencode($search),
 				[
 					'timeout' => 10,
 					'connect_timeout' => 3,
+					'verify' => !($isGlobalScaleEnabled && $this->config->getSystemValueBool('gss.selfsigned.allow', false) === true)
 				]
 			);