diff --git a/src/Plugin/search_api/processor/Highlight.php b/src/Plugin/search_api/processor/Highlight.php
index 5d35012b..276097b0 100644
--- a/src/Plugin/search_api/processor/Highlight.php
+++ b/src/Plugin/search_api/processor/Highlight.php
@@ -473,7 +473,7 @@ class Highlight extends ProcessorPluginBase implements PluginFormInterface {
     $text = preg_replace('#<(style|script).*?>.*?</\1>#is', ' ', $text);
 
     // Prepare text by stripping HTML tags and decoding HTML entities.
-    $text = strip_tags(str_replace(['<', '>'], [' <', '> '], $text));
+    $text = strip_tags(str_replace(['<', '>'], [' <', '> '], $text ?? ''));
     $text = Html::decodeEntities($text);
     $text = preg_replace('/\s+/', ' ', $text);
     $text = trim($text, ' ');