diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index e843604c3a4f..955267bbc2be 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -610,8 +610,8 @@ static unsigned int msi_domain_get_hwsize(struct device *dev, unsigned int domid
 		info = domain->host_data;
 		return info->hwsize;
 	}
-	/* No domain, no size... */
-	return 0;
+	/* No domain, default to MSI_XA_DOMAIN_SIZE */
+	return MSI_XA_DOMAIN_SIZE;
 }
 
 static inline void irq_chip_write_msi_msg(struct irq_data *data,