diff --git a/htdocs/core/class/infobox.class.php b/htdocs/core/class/infobox.class.php
index 9254e0b0f64..679c2977dec 100644
--- a/htdocs/core/class/infobox.class.php
+++ b/htdocs/core/class/infobox.class.php
@@ -114,7 +114,7 @@ class InfoBox
 			$sql .= " ORDER BY b.box_order";
 		} else { // available
 			$sql = "SELECT d.rowid as box_id, d.file, d.note, d.tms";
-			$sql .= " FROM ".$this->db->prefix()."boxes_def as d";
+			$sql .= " FROM ".$db->prefix()."boxes_def as d";
 			$sql .= " WHERE d.entity IN (0, ".$conf->entity.")";
 		}
 
diff --git a/test/phpunit/CodingPhpTest.php b/test/phpunit/CodingPhpTest.php
index 51cdddbd422..0620098a3f9 100644
--- a/test/phpunit/CodingPhpTest.php
+++ b/test/phpunit/CodingPhpTest.php
@@ -213,6 +213,7 @@ class CodingPhpTest extends PHPUnit\Framework\TestCase
 					'multicurrency.class.php',
 					'productbatch.class.php',
 					'reception.class.php',
+					'infobox.class.php',
 				))) {
 					// Must not find $db->
 					$ok=true;