diff --git a/htdocs/accountancy/expensereport/lines.php b/htdocs/accountancy/expensereport/lines.php
index 11602a58f1f..60f08f4992d 100644
--- a/htdocs/accountancy/expensereport/lines.php
+++ b/htdocs/accountancy/expensereport/lines.php
@@ -279,22 +279,22 @@ if ($result) {
 		$param .= "&search_vat=".urlencode($search_vat);
 	}
 	if ($search_date_startday) {
-		$param .= '&search_date_startday='.urlencode($search_date_startday);
+		$param .= '&search_date_startday='.urlencode((string) ($search_date_startday));
 	}
 	if ($search_date_startmonth) {
-		$param .= '&search_date_startmonth='.urlencode($search_date_startmonth);
+		$param .= '&search_date_startmonth='.urlencode((string) ($search_date_startmonth));
 	}
 	if ($search_date_startyear) {
-		$param .= '&search_date_startyear='.urlencode($search_date_startyear);
+		$param .= '&search_date_startyear='.urlencode((string) ($search_date_startyear));
 	}
 	if ($search_date_endday) {
-		$param .= '&search_date_endday='.urlencode($search_date_endday);
+		$param .= '&search_date_endday='.urlencode((string) ($search_date_endday));
 	}
 	if ($search_date_endmonth) {
-		$param .= '&search_date_endmonth='.urlencode($search_date_endmonth);
+		$param .= '&search_date_endmonth='.urlencode((string) ($search_date_endmonth));
 	}
 	if ($search_date_endyear) {
-		$param .= '&search_date_endyear='.urlencode($search_date_endyear);
+		$param .= '&search_date_endyear='.urlencode((string) ($search_date_endyear));
 	}
 
 	print '<form action="'.$_SERVER["PHP_SELF"].'" method="post">'."\n";