diff --git a/modules/ppcp-settings/services.php b/modules/ppcp-settings/services.php
index ef9b0c55d..723eaad74 100644
--- a/modules/ppcp-settings/services.php
+++ b/modules/ppcp-settings/services.php
@@ -121,7 +121,8 @@ return array(
 	},
 	'settings.data.settings'                              => static function ( ContainerInterface $container ) : SettingsModel {
 		return new SettingsModel(
-			$container->get( 'settings.service.sanitizer' )
+			$container->get( 'settings.service.sanitizer' ),
+			$container->has( 'wcgateway.settings.invoice-prefix' ) ? $container->get( 'wcgateway.settings.invoice-prefix' ) : ''
 		);
 	},
 	'settings.data.paylater-messaging'                    => static function ( ContainerInterface $container ) : array {
diff --git a/modules/ppcp-settings/src/Data/SettingsModel.php b/modules/ppcp-settings/src/Data/SettingsModel.php
index 099b7b6a6..a9f587a3a 100644
--- a/modules/ppcp-settings/src/Data/SettingsModel.php
+++ b/modules/ppcp-settings/src/Data/SettingsModel.php
@@ -47,14 +47,24 @@ class SettingsModel extends AbstractDataModel {
 	 */
 	protected DataSanitizer $sanitizer;
 
+	/**
+	 * Invoice prefix.
+	 *
+	 * @var string
+	 */
+	private string $invoice_prefix;
+
 	/**
 	 * Constructor.
 	 *
 	 * @param DataSanitizer $sanitizer Data sanitizer service.
+	 * @param string        $invoice_prefix Invoice prefix.
 	 * @throws RuntimeException If the OPTION_KEY is not defined in the child class.
 	 */
-	public function __construct( DataSanitizer $sanitizer ) {
-		$this->sanitizer = $sanitizer;
+	public function __construct( DataSanitizer $sanitizer, string $invoice_prefix ) {
+		$this->sanitizer      = $sanitizer;
+		$this->invoice_prefix = $invoice_prefix;
+
 		parent::__construct();
 	}
 
@@ -66,7 +76,7 @@ class SettingsModel extends AbstractDataModel {
 	protected function get_defaults() : array {
 		return array(
 			// Free-form string values.
-			'invoice_prefix'         => '',
+			'invoice_prefix'         => $this->invoice_prefix,
 			'brand_name'             => '',
 			'soft_descriptor'        => '',
 
diff --git a/modules/ppcp-wc-gateway/services.php b/modules/ppcp-wc-gateway/services.php
index a149b4913..e81c040fe 100644
--- a/modules/ppcp-wc-gateway/services.php
+++ b/modules/ppcp-wc-gateway/services.php
@@ -2093,4 +2093,16 @@ return array(
 	'wcgateway.settings.admin-settings-enabled'            => static function( ContainerInterface $container ): bool {
 		return $container->has( 'settings.url' ) && ! SettingsModule::should_use_the_old_ui();
 	},
+
+	/**
+	 * Returns a prefix for the site, ensuring the same site always gets the same prefix (unless the URL changes).
+	 */
+	'wcgateway.settings.invoice-prefix'                    => static function( ContainerInterface $container ): string {
+		$site_url = get_site_url( get_current_blog_id() );
+		$hash     = md5( $site_url );
+		$letters  = preg_replace( '~\d~', '', $hash ) ?? '';
+		$prefix   = substr( $letters, 0, 6 );
+
+		return $prefix ? $prefix . '-' : '';
+	},
 );
diff --git a/modules/ppcp-wc-gateway/src/Settings/Fields/connection-tab-fields.php b/modules/ppcp-wc-gateway/src/Settings/Fields/connection-tab-fields.php
index a897f78ba..24a1b1505 100644
--- a/modules/ppcp-wc-gateway/src/Settings/Fields/connection-tab-fields.php
+++ b/modules/ppcp-wc-gateway/src/Settings/Fields/connection-tab-fields.php
@@ -510,13 +510,7 @@ return function ( ContainerInterface $container, array $fields ): array {
 			'custom_attributes' => array(
 				'pattern' => '[a-zA-Z_\\-]+',
 			),
-			'default'           => ( static function (): string {
-				$site_url = get_site_url( get_current_blog_id() );
-				$hash = md5( $site_url );
-				$letters = preg_replace( '~\d~', '', $hash ) ?? '';
-				$prefix = substr( $letters, 0, 6 );
-				return $prefix ? $prefix . '-' : '';
-			} )(),
+			'default'           => $container->get( 'wcgateway.settings.invoice-prefix' ),
 			'screens'           => array(
 				State::STATE_START,
 				State::STATE_ONBOARDED,
@@ -539,7 +533,7 @@ return function ( ContainerInterface $container, array $fields ): array {
 			'requirements' => array(),
 			'gateway'      => Settings::CONNECTION_TAB_ID,
 		),
-		'stay_updated'                               => array(
+		'stay_updated'                                  => array(
 			'title'        => __( 'Stay Updated', 'woocommerce-paypal-payments' ),
 			'type'         => 'checkbox',
 			'desc_tip'     => true,