diff --git a/htdocs/asset/class/asset.class.php b/htdocs/asset/class/asset.class.php
index 01184bf45b0..0c8c61e0d1f 100644
--- a/htdocs/asset/class/asset.class.php
+++ b/htdocs/asset/class/asset.class.php
@@ -1014,6 +1014,8 @@ class Asset extends CommonObject
 				$nb_days_in_month = getDolGlobalString('ASSET_DEPRECIATION_DURATION_PER_MONTH') ? $conf->global->ASSET_DEPRECIATION_DURATION_PER_MONTH : 30;
 				$period_amount = (float) price2num($depreciation_period_amount / $fields['duration'], 'MT');
 				$first_period_found = false;
+				// TODO fix declaration of $begin_period
+				// @phpstan-ignore-next-line
 				$first_period_date = isset($begin_period) && $begin_period > $fiscal_period_start ? $begin_period : $fiscal_period_start;
 
 				$ref_date_format = "%Y" . ($fields['duration_type'] == 1 || $fields['duration_type'] == 2 ? '-%m' : '') . ($fields['duration_type'] == 2 ? '-%d' : '');