diff --git a/includes/plugins/wc-memberships/class-membership-expiry.php b/includes/plugins/wc-memberships/class-membership-expiry.php
index 061d33c0ac..c070aae7c3 100644
--- a/includes/plugins/wc-memberships/class-membership-expiry.php
+++ b/includes/plugins/wc-memberships/class-membership-expiry.php
@@ -28,13 +28,18 @@ public static function init() {
 	/**
 	 * Prevent membership expiration if there are other active subscriptions.
 	 *
-	 * @param bool                                                      $cancel_membership Whether to cancel the membership when the subscription is cancelled (default true).
-	 * @param \WC_Memberships_Integration_Subscriptions_User_Membership $user_membership The subscription-tied membership.
+	 * @param bool                            $cancel_membership Whether to cancel the membership when the subscription is cancelled (default true).
+	 * @param \WC_Memberships_User_Membership $user_membership   The membership. Only subscription-tied memberships (\WC_Memberships_Integration_Subscriptions_User_Membership) expose get_subscription_id()/set_subscription_id().
 	 */
 	public static function prevent_membership_expiration( $cancel_membership, $user_membership ) {
 		if ( ! function_exists( 'wcs_get_subscription' ) ) {
 			return $cancel_membership;
 		}
+		// `wc_memberships_expire_user_membership` fires for every membership, but only the
+		// Subscriptions integration class exposes get_subscription_id()/set_subscription_id().
+		if ( ! method_exists( $user_membership, 'get_subscription_id' ) ) {
+			return $cancel_membership;
+		}
 		$membership_product_id = $user_membership->get_product_id();
 		$cancelling_subscription_id = $user_membership->get_subscription_id();
 		$active_subscription_ids = WooCommerce_Connection::get_active_subscriptions_for_user( $user_membership->get_user_id() );
diff --git a/tests/unit-tests/plugins/wc-memberships/membership-expiry.php b/tests/unit-tests/plugins/wc-memberships/membership-expiry.php
new file mode 100644
index 0000000000..3180f945c2
--- /dev/null
+++ b/tests/unit-tests/plugins/wc-memberships/membership-expiry.php
@@ -0,0 +1,54 @@
+<?php
+/**
+ * Tests for the WC Memberships expiry handler.
+ *
+ * @package Newspack\Tests
+ */
+
+use Newspack\Membership_Expiry;
+
+require_once dirname( __DIR__, 3 ) . '/mocks/wc-mocks.php';
+
+/**
+ * Test Membership_Expiry::prevent_membership_expiration().
+ *
+ * @group membership-expiry
+ */
+class Test_Membership_Expiry extends WP_UnitTestCase {
+
+	/**
+	 * The wc_memberships_expire_user_membership filter fires for every user membership,
+	 * not just subscription-tied ones. Plain WC_Memberships_User_Membership objects do
+	 * not expose get_subscription_id(); calling it must not fatal.
+	 *
+	 * Reproduces the production fatal observed at v6.39.3 of newspack-plugin:
+	 *   Uncaught Error: Call to undefined method WC_Memberships_User_Membership::get_subscription_id()
+	 *   in includes/plugins/wc-memberships/class-membership-expiry.php:39
+	 */
+	public function test_passes_through_non_subscription_membership() {
+		$non_subscription_membership = new class() {
+			/**
+			 * Return a product id.
+			 *
+			 * @return int
+			 */
+			public function get_product_id() {
+				return 123;
+			}
+
+			/**
+			 * Return a user id.
+			 *
+			 * @return int
+			 */
+			public function get_user_id() {
+				return 456;
+			}
+
+			// Deliberately no get_subscription_id() — only the Subscriptions integration class has it.
+		};
+
+		$result = Membership_Expiry::prevent_membership_expiration( true, $non_subscription_membership );
+		$this->assertTrue( $result, 'Filter should return the incoming $cancel_membership unchanged when the membership is not subscription-tied.' );
+	}
+}