diff --git a/formats/carousel/Carousel.php b/formats/carousel/Carousel.php
index d8398f4f1..34ddfcfd5 100644
--- a/formats/carousel/Carousel.php
+++ b/formats/carousel/Carousel.php
@@ -513,7 +513,7 @@ protected function getResultText( QueryResult $results, $outputmode ) {
 
 			$imgAttr = [
 				'src' => $imageValue,
-				'alt' => ( $titleValue ?? $captionValue ? strip_tags( $captionValue ) : $title_->getText() ),
+				'alt' => ( $titleValue ?? $captionValue ? strip_tags( $captionValue ?? '' ) : $title_->getText() ),
 				'class' => "slick-slide-content img"
 			];
 
diff --git a/formats/slideshow/SRF_SlideShow.php b/formats/slideshow/SRF_SlideShow.php
index 0b6d1fcde..d7a321ee4 100644
--- a/formats/slideshow/SRF_SlideShow.php
+++ b/formats/slideshow/SRF_SlideShow.php
@@ -117,7 +117,7 @@ protected function getResultText( QueryResult $res, $outputmode ) {
 	 *
 	 * @return bool
 	 */
-	protected function linkFurtherResults( QueryResult $results ) {
+	protected function linkFurtherResults( QueryResult $results ): bool {
 		return false;
 	}