diff --git a/src/acpi.c b/src/acpi.c
index 3699898..1994838 100644
--- a/src/acpi.c
+++ b/src/acpi.c
@@ -18,6 +18,8 @@
 
 #include "acpi-dsdt.hex"
 
+u32 acpi_pm1a_cnt VARFSEG;
+
 static void
 build_header(struct acpi_table_header *h, u32 sig, int len, u8 rev)
 {
@@ -730,9 +732,12 @@
     if (!fadt)
         return;
     u32 pm_tmr = le32_to_cpu(fadt->pm_tmr_blk);
+    u32 pm1a_cnt = le32_to_cpu(fadt->pm1a_cnt_blk);
     dprintf(4, "pm_tmr_blk=%x\n", pm_tmr);
     if (pm_tmr)
         pmtimer_setup(pm_tmr, 3579);
+    if (pm1a_cnt)
+        acpi_pm1a_cnt = pm1a_cnt;
 
     // Theoretically we should check the 'reset_reg_sup' flag, but Windows
     // doesn't and thus nobody seems to *set* it. If the table is large enough
diff --git a/src/acpi.h b/src/acpi.h
index 5d1e104..f0d24d4 100644
--- a/src/acpi.h
+++ b/src/acpi.h
@@ -36,6 +36,7 @@
 };
 
 extern struct rsdp_descriptor *RsdpAddr;
+extern u32 acpi_pm1a_cnt;
 
 /* Table structure from Linux kernel (the ACPI tables are under the
    BSD license) */
diff --git a/src/apm.c b/src/apm.c
index b2eac6d..de6bd99 100644
--- a/src/apm.c
+++ b/src/apm.c
@@ -12,6 +12,7 @@
 #include "config.h" // CONFIG_*
 #include "biosvar.h" // GET_GLOBAL
 #include "paravirt.h" // runningOnQEMU
+#include "acpi.h" // acpi_pm_ctl
 
 static void
 out_str(const char *str_cs)
@@ -108,7 +109,11 @@
 void
 apm_shutdown(void)
 {
+    u16 pm1a_cnt = GET_GLOBAL(acpi_pm1a_cnt);
+
     irq_disable();
+    if (pm1a_cnt)
+        outw(0x2000, pm1a_cnt);
     out_str("Shutdown");
     for (;;)
         hlt();
diff --git a/src/pciinit.c b/src/pciinit.c
index 8370b96..0c6b0cb 100644
--- a/src/pciinit.c
+++ b/src/pciinit.c
@@ -15,6 +15,7 @@
 #include "paravirt.h" // RamSize
 #include "dev-q35.h" // Q35_HOST_BRIDGE_PCIEXBAR_ADDR
 #include "list.h" // struct hlist_node
+#include "acpi.h" // acpi_pm1a_cnt
 
 /* PM Timer ticks per second (HZ) */
 #define PM_TIMER_FREQUENCY  3579545
@@ -194,6 +195,7 @@
     /* acpi enable, SCI: IRQ9 000b = irq9*/
     pci_config_writeb(bdf, ICH9_LPC_ACPI_CTRL, ICH9_LPC_ACPI_CTRL_ACPI_EN);
 
+    acpi_pm1a_cnt = PORT_ACPI_PM_BASE + 0x04;
     pmtimer_setup(PORT_ACPI_PM_BASE + 0x08, PM_TIMER_FREQUENCY / 1000);
 }
 
@@ -238,6 +240,7 @@
     pci_config_writel(bdf, 0x90, PORT_SMB_BASE | 1);
     pci_config_writeb(bdf, 0xd2, 0x09); /* enable SMBus io space */
 
+    acpi_pm1a_cnt = PORT_ACPI_PM_BASE + 0x04;
     pmtimer_setup(PORT_ACPI_PM_BASE + 0x08, PM_TIMER_FREQUENCY / 1000);
 }