diff --git a/hw/slavio_serial.c b/hw/slavio_serial.c
index bd572b03fd7454baa8b6ff61cacf8e89e3aab94d..03bd534bd5e254ad348e8eb6b2c6731f4a0d26fb 100644
--- a/hw/slavio_serial.c
+++ b/hw/slavio_serial.c
@@ -514,9 +514,13 @@ static void slavio_serial_mem_writeb(void *opaque, target_phys_addr_t addr,
             break;
         case W_TXCTRL1:
         case W_TXCTRL2:
+            s->wregs[s->reg] = val;
+            slavio_serial_update_parameters(s);
+            break;
         case W_BRGLO:
         case W_BRGHI:
             s->wregs[s->reg] = val;
+            s->rregs[s->reg] = val;
             slavio_serial_update_parameters(s);
             break;
         case W_MINTR: