diff --git a/htdocs/compta/facture/class/api_invoices.class.php b/htdocs/compta/facture/class/api_invoices.class.php
index b913b405734..0ab4974ce7f 100644
--- a/htdocs/compta/facture/class/api_invoices.class.php
+++ b/htdocs/compta/facture/class/api_invoices.class.php
@@ -1499,7 +1499,7 @@ class Invoices extends DolibarrApi
         	    $amount = price2num($amountarray["multicurrency_amount"], 'MT');
         	}
 
-			if ($amount > $remainstopay && $accepthigherpayment == false) {
+			if ($amount > $remainstopay && !$accepthigherpayment) {
 				$this->db->rollback();
         		throw new RestException(400, 'Payment amount on invoice ID '.$id.' ('.$amount.') is higher than remain to pay ('.$remainstopay.')');
 			}