diff --git a/modules/ppcp-wc-gateway/src/Gateway/PayUponInvoice/PayUponInvoice.php b/modules/ppcp-wc-gateway/src/Gateway/PayUponInvoice/PayUponInvoice.php
index 355ef3f3b..1bc41c257 100644
--- a/modules/ppcp-wc-gateway/src/Gateway/PayUponInvoice/PayUponInvoice.php
+++ b/modules/ppcp-wc-gateway/src/Gateway/PayUponInvoice/PayUponInvoice.php
@@ -272,7 +272,7 @@ class PayUponInvoice {
 				}
 
 				$birth_date = filter_input( INPUT_POST, 'billing_birth_date', FILTER_SANITIZE_STRING );
-				if ( ! $this->pui_helper->validate_birth_date( $birth_date ) ) {
+				if ( $birth_date && ! $this->pui_helper->validate_birth_date( $birth_date ) ) {
 					$errors->add( 'validation', __( 'Invalid birth date.', 'woocommerce-paypal-payments' ) );
 				}
 			},
diff --git a/modules/ppcp-wc-gateway/src/Helper/PayUponInvoiceHelper.php b/modules/ppcp-wc-gateway/src/Helper/PayUponInvoiceHelper.php
index cd7c6c491..ce2dc1b8c 100644
--- a/modules/ppcp-wc-gateway/src/Helper/PayUponInvoiceHelper.php
+++ b/modules/ppcp-wc-gateway/src/Helper/PayUponInvoiceHelper.php
@@ -33,7 +33,8 @@ class PayUponInvoiceHelper {
 			return false;
 		}
 
-		if ( time() < strtotime( '+18 years', strtotime( $date ) ) ) {
+		$date_time = strtotime( $date );
+		if ( $date_time && time() < strtotime( '+18 years', $date_time ) ) {
 			return false;
 		}
 
diff --git a/tests/PHPUnit/WcGateway/Helper/PayUponInvoiceHelperTest.php b/tests/PHPUnit/WcGateway/Helper/PayUponInvoiceHelperTest.php
index 5a073c95a..3a1d9bdc0 100644
--- a/tests/PHPUnit/WcGateway/Helper/PayUponInvoiceHelperTest.php
+++ b/tests/PHPUnit/WcGateway/Helper/PayUponInvoiceHelperTest.php
@@ -23,7 +23,7 @@ class PayUponInvoiceHelperTest extends TestCase
 			['', false],
 			[(new DateTime())->format($format), false],
 			[(new DateTime('-17 years'))->format($format), false],
-			['31-02-1942', false],
+			['1942-02-31', false],
 			['01-01-1942', false],
 			['1942-01-01', true],
 		];