diff --git a/htdocs/product/class/propalmergepdfproduct.class.php b/htdocs/product/class/propalmergepdfproduct.class.php
index 67c24ac37c8..a37ca09101b 100644
--- a/htdocs/product/class/propalmergepdfproduct.class.php
+++ b/htdocs/product/class/propalmergepdfproduct.class.php
@@ -233,7 +233,7 @@ class Propalmergepdfproduct extends CommonObject
 
 		$sql .= " FROM ".MAIN_DB_PREFIX."propal_merge_pdf_product as t";
 		$sql .= " WHERE t.fk_product = ".((int) $product_id);
-		if ($conf->global->MAIN_MULTILANGS && !empty($lang)) {
+		if (!empty($conf->global->MAIN_MULTILANGS) && !empty($lang)) {
 			$sql .= " AND t.lang = '".$this->db->escape($lang)."'";
 		}