diff --git a/includes/Hooks/SearchResultProvideThumbnailHookHandler.php b/includes/Hooks/SearchResultProvideThumbnailHookHandler.php
index d903e44..5c39078 100644
--- a/includes/Hooks/SearchResultProvideThumbnailHookHandler.php
+++ b/includes/Hooks/SearchResultProvideThumbnailHookHandler.php
@@ -53,7 +53,7 @@ class SearchResultProvideThumbnailHookHandler implements SearchResultProvideThum
 		$propValues = $this->pageProps->getProperties(
 			$nonFileIdentitiesByPageId,
 			// T320661: only provide free images for search purposes
-			PageImages::getPropNames( PageImages::LICENSE_FREE )
+			(array)PageImages::getPropNames( PageImages::LICENSE_FREE )
 		);
 		$fileNames = array_map( static function ( $prop ) {
 			return $prop[ PageImages::getPropName( false ) ]
diff --git a/tests/phpunit/Hooks/SearchResultProvideThumbnailHookHandlerTest.php b/tests/phpunit/Hooks/SearchResultProvideThumbnailHookHandlerTest.php
index 751bc67..b5b4582 100644
--- a/tests/phpunit/Hooks/SearchResultProvideThumbnailHookHandlerTest.php
+++ b/tests/phpunit/Hooks/SearchResultProvideThumbnailHookHandlerTest.php
@@ -116,7 +116,7 @@ class SearchResultProvideThumbnailHookHandlerTest extends MediaWikiIntegrationTe
 			->method( 'getProperties' )
 			->with(
 				$this->anything(),
-				PageImages::getPropNames( PageImages::LICENSE_FREE )
+				(array)PageImages::getPropNames( PageImages::LICENSE_FREE )
 			)->willReturn( [
 				1 => [
 					PageImages::getPropName( true ) => 'File1_free.jpg'