diff --git a/htdocs/core/class/commoninvoice.class.php b/htdocs/core/class/commoninvoice.class.php
index a8b248dd38e..2e2a26dd9ae 100644
--- a/htdocs/core/class/commoninvoice.class.php
+++ b/htdocs/core/class/commoninvoice.class.php
@@ -91,8 +91,8 @@ abstract class CommonInvoice extends CommonObject
 
 	
 	/**
-	 * 	Return remain amount to pay.
-	 *  Property ->id and ->total_ttc must be set.
+	 * 	Return remain amount to pay. Property ->id and ->total_ttc must be set.
+	 *  This does not include open direct debit requests.
 	 *
 	 *  @param 		int 	$multicurrency 	Return multicurrency_amount instead of amount
 	 *	@return		int						Remain of amount to pay