diff --git a/src/Debug.php b/src/Debug.php
index 6e05911..ce5ea76 100644
--- a/src/Debug.php
+++ b/src/Debug.php
@@ -103,7 +103,7 @@ public function getLinesTable(array $lines)
             $_lines[] = [
                 $line->getIndex(),
                 $line->getInput(),
-                htmlentities($line->output, ENT_QUOTES),
+                htmlentities((string) $line->output, ENT_QUOTES),
                 htmlentities($line->renderPrepend(), ENT_QUOTES),
                 implode(", ", $line->getDebugInfo()),
                 var_export($line->getAttributes(), true),