diff --git a/htdocs/comm/propal/card.php b/htdocs/comm/propal/card.php
index e31b43f5a43..6ec18e6d808 100644
--- a/htdocs/comm/propal/card.php
+++ b/htdocs/comm/propal/card.php
@@ -976,6 +976,11 @@ if (empty($reshook)) {
 			$idprod = 0;
 		} else {
 			$idprod = GETPOST('idprod', 'int');
+
+			if (!empty($conf->global->MAIN_DISABLE_FREE_LINES) && $idprod <= 0) {
+				setEventMessages($langs->trans("ErrorFieldRequired", $langs->transnoentitiesnoconv("ProductOrService")), null, 'errors');
+				$error++;
+			}
 		}
 
 		$tva_tx = GETPOST('tva_tx', 'alpha');
diff --git a/htdocs/commande/card.php b/htdocs/commande/card.php
index c6ebb04eb03..0c9795ae9ec 100644
--- a/htdocs/commande/card.php
+++ b/htdocs/commande/card.php
@@ -686,6 +686,11 @@ if (empty($reshook)) {
 			$idprod = 0;
 		} else {
 			$idprod = GETPOST('idprod', 'int');
+
+			if (!empty($conf->global->MAIN_DISABLE_FREE_LINES) && $idprod <= 0) {
+				setEventMessages($langs->trans("ErrorFieldRequired", $langs->transnoentitiesnoconv("ProductOrService")), null, 'errors');
+				$error++;
+			}
 		}
 
 		$tva_tx = GETPOST('tva_tx', 'alpha');
diff --git a/htdocs/compta/facture/card-rec.php b/htdocs/compta/facture/card-rec.php
index a2a87d6d64a..4efbabbaf49 100644
--- a/htdocs/compta/facture/card-rec.php
+++ b/htdocs/compta/facture/card-rec.php
@@ -433,6 +433,11 @@ if (empty($reshook)) {
 		} else {
 			$idprod = GETPOST('idprod', 'int');
 			$tva_tx = '';
+
+			if (!empty($conf->global->MAIN_DISABLE_FREE_LINES) && $idprod <= 0) {
+				setEventMessages($langs->trans("ErrorFieldRequired", $langs->transnoentitiesnoconv("ProductOrService")), null, 'errors');
+				$error++;
+			}
 		}
 
 		$qty = price2num(GETPOST('qty'.$predef, 'alpha'), 'MS', 2);
diff --git a/htdocs/compta/facture/card.php b/htdocs/compta/facture/card.php
index afff624102b..e904a11283c 100644
--- a/htdocs/compta/facture/card.php
+++ b/htdocs/compta/facture/card.php
@@ -2042,6 +2042,11 @@ if (empty($reshook)) {
 			$idprod = 0;
 		} else {
 			$idprod = GETPOST('idprod', 'int');
+
+			if (!empty($conf->global->MAIN_DISABLE_FREE_LINES) && $idprod <= 0) {
+				setEventMessages($langs->trans("ErrorFieldRequired", $langs->transnoentitiesnoconv("ProductOrService")), null, 'errors');
+				$error++;
+			}
 		}
 
 		$tva_tx = GETPOST('tva_tx', 'alpha');
diff --git a/htdocs/contrat/card.php b/htdocs/contrat/card.php
index 0b45cb88215..b89dea64cc7 100644
--- a/htdocs/contrat/card.php
+++ b/htdocs/contrat/card.php
@@ -441,6 +441,11 @@ if (empty($reshook)) {
 			$idprod = 0;
 		} else {
 			$idprod = GETPOST('idprod', 'int');
+
+			if (!empty($conf->global->MAIN_DISABLE_FREE_LINES) && $idprod <= 0) {
+				setEventMessages($langs->trans("ErrorFieldRequired", $langs->transnoentitiesnoconv("ProductOrService")), null, 'errors');
+				$error++;
+			}
 		}
 
 		$tva_tx = GETPOST('tva_tx', 'alpha');