diff --git a/system/Debug/Toolbar.php b/system/Debug/Toolbar.php
index f67bffb2fbe9..e046ec4afa42 100644
--- a/system/Debug/Toolbar.php
+++ b/system/Debug/Toolbar.php
@@ -141,7 +141,7 @@ public function run($startTime, $totalTime, $request, $response): string
 			foreach ($_SESSION as $key => $value)
 			{
 				// Replace the binary data with string to avoid json_encode failure.
-				if (preg_match('~[^\x20-\x7E\t\r\n]~', $value))
+				if (is_string($value) && preg_match('~[^\x20-\x7E\t\r\n]~', $value))
 				{
 					$value = 'binary data';
 				}