diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c
index 3bd1d5a865..3af0fa726c 100644
--- a/hw/acpi/piix4.c
+++ b/hw/acpi/piix4.c
@@ -112,6 +112,9 @@ static void apm_ctrl_changed(uint32_t val, void *arg)
 
     /* ACPI specs 3.0, 4.7.2.5 */
     acpi_pm1_cnt_update(&s->ar, val == ACPI_ENABLE, val == ACPI_DISABLE);
+    if (val == ACPI_ENABLE || val == ACPI_DISABLE) {
+        return;
+    }
 
     if (d->config[0x5b] & (1 << 1)) {
         if (s->smi_irq) {
diff --git a/hw/isa/lpc_ich9.c b/hw/isa/lpc_ich9.c
index b3e0b1fd52..341a727f9f 100644
--- a/hw/isa/lpc_ich9.c
+++ b/hw/isa/lpc_ich9.c
@@ -375,6 +375,9 @@ static void ich9_apm_ctrl_changed(uint32_t val, void *arg)
     acpi_pm1_cnt_update(&lpc->pm.acpi_regs,
                         val == ICH9_APM_ACPI_ENABLE,
                         val == ICH9_APM_ACPI_DISABLE);
+    if (val == ICH9_APM_ACPI_ENABLE || val == ICH9_APM_ACPI_DISABLE) {
+        return;
+    }
 
     /* SMI_EN = PMBASE + 30. SMI control and enable register */
     if (lpc->pm.smi_en & ICH9_PMIO_SMI_EN_APMC_EN) {