diff --git a/htdocs/webservices/server_invoice.php b/htdocs/webservices/server_invoice.php
index ff82b33d4db..b218fefe070 100755
--- a/htdocs/webservices/server_invoice.php
+++ b/htdocs/webservices/server_invoice.php
@@ -191,7 +191,7 @@ $ns
 /**
  * Get invoice from id, ref or ref_ext
  */
-function getInvoice($authentication,$id,$ref,$ref_ext)
+function getInvoice($authentication,$id='',$ref='',$ref_ext='')
 {
 	global $db,$conf,$langs;
 
diff --git a/htdocs/webservices/server_thirdparty.php b/htdocs/webservices/server_thirdparty.php
index 996b84a6542..62b6d6bb65d 100755
--- a/htdocs/webservices/server_thirdparty.php
+++ b/htdocs/webservices/server_thirdparty.php
@@ -126,7 +126,7 @@ $ns
 
 
 // Full methods code
-function getThirdParty($authentication,$id,$ref,$ref_ext)
+function getThirdParty($authentication,$id='',$ref='',$ref_ext='')
 {
 	global $db,$conf,$langs;