diff --git a/htdocs/comm/propal/class/propal.class.php b/htdocs/comm/propal/class/propal.class.php
index 9227e57fca3..8f9b45de555 100644
--- a/htdocs/comm/propal/class/propal.class.php
+++ b/htdocs/comm/propal/class/propal.class.php
@@ -272,12 +272,12 @@ class Propal extends CommonObject
 	public $address;
 
 	/**
-	 * @var int availability ID
+	 * @var ?int availability ID can be null in db
 	 */
 	public $availability_id;
 
 	/**
-	 * @var int availability ID
+	 * @var ?int availability ID
 	 * @deprecated
 	 * @see $availability_id
 	 */
diff --git a/htdocs/core/class/commonobject.class.php b/htdocs/core/class/commonobject.class.php
index d45f07f6a7e..a38c8db46e1 100644
--- a/htdocs/core/class/commonobject.class.php
+++ b/htdocs/core/class/commonobject.class.php
@@ -490,7 +490,7 @@ abstract class CommonObject
 	public $fk_delivery_address;
 
 	/**
-	 * @var int 		Shipping method ID
+	 * @var ?int 		Shipping method ID
 	 * @see setShippingMethod()
 	 */
 	public $shipping_method_id;
diff --git a/htdocs/holiday/class/holiday.class.php b/htdocs/holiday/class/holiday.class.php
index eef13c94d9b..0133135b05e 100644
--- a/htdocs/holiday/class/holiday.class.php
+++ b/htdocs/holiday/class/holiday.class.php
@@ -898,8 +898,9 @@ class Holiday extends CommonObject
 		if ($checkBalance > 0) {
 			$balance = $this->getCPforUser($this->fk_user, $this->fk_type);
 
-			$days = num_between_day($this->date_debut, $this->date_fin);
-			if ($balance - $days < 0 && getDolGlobalString('HOLIDAY_DISALLOW_NEGATIVE_BALANCE')) {
+			$days = num_public_holiday($this->date_debut, $this->date_fin);
+
+			if ((($balance - $days) < 0) && getDolGlobalString('HOLIDAY_DISALLOW_NEGATIVE_BALANCE')) {
 				$this->error = 'LeaveRequestCreationBlockedBecauseBalanceIsNegative';
 				return -1;
 			}