diff --git a/hw/acpi/core.c b/hw/acpi/core.c
index 6da275c599..00b1e79a30 100644
--- a/hw/acpi/core.c
+++ b/hw/acpi/core.c
@@ -551,8 +551,35 @@ void acpi_pm_tmr_reset(ACPIREGS *ar)
 }
 
 /* ACPI PM1aCNT */
-static void acpi_pm1_cnt_write(ACPIREGS *ar, uint16_t val)
+void acpi_pm1_cnt_update(ACPIREGS *ar,
+                         bool sci_enable, bool sci_disable)
 {
+    /* ACPI specs 3.0, 4.7.2.5 */
+    if (ar->pm1.cnt.acpi_only) {
+        return;
+    }
+
+    if (sci_enable) {
+        ar->pm1.cnt.cnt |= ACPI_BITMASK_SCI_ENABLE;
+    } else if (sci_disable) {
+        ar->pm1.cnt.cnt &= ~ACPI_BITMASK_SCI_ENABLE;
+    }
+}
+
+static uint64_t acpi_pm_cnt_read(void *opaque, hwaddr addr, unsigned width)
+{
+    ACPIREGS *ar = opaque;
+    return ar->pm1.cnt.cnt >> addr * 8;
+}
+
+static void acpi_pm_cnt_write(void *opaque, hwaddr addr, uint64_t val,
+                              unsigned width)
+{
+    ACPIREGS *ar = opaque;
+
+    if (addr == 1) {
+        val = val << 8 | (ar->pm1.cnt.cnt & 0xff);
+    }
     ar->pm1.cnt.cnt = val & ~(ACPI_BITMASK_SLEEP_ENABLE);
 
     if (val & ACPI_BITMASK_SLEEP_ENABLE) {
@@ -575,33 +602,6 @@ static void acpi_pm1_cnt_write(ACPIREGS *ar, uint16_t val)
     }
 }
 
-void acpi_pm1_cnt_update(ACPIREGS *ar,
-                         bool sci_enable, bool sci_disable)
-{
-    /* ACPI specs 3.0, 4.7.2.5 */
-    if (ar->pm1.cnt.acpi_only) {
-        return;
-    }
-
-    if (sci_enable) {
-        ar->pm1.cnt.cnt |= ACPI_BITMASK_SCI_ENABLE;
-    } else if (sci_disable) {
-        ar->pm1.cnt.cnt &= ~ACPI_BITMASK_SCI_ENABLE;
-    }
-}
-
-static uint64_t acpi_pm_cnt_read(void *opaque, hwaddr addr, unsigned width)
-{
-    ACPIREGS *ar = opaque;
-    return ar->pm1.cnt.cnt;
-}
-
-static void acpi_pm_cnt_write(void *opaque, hwaddr addr, uint64_t val,
-                              unsigned width)
-{
-    acpi_pm1_cnt_write(opaque, val);
-}
-
 static const MemoryRegionOps acpi_pm_cnt_ops = {
     .read = acpi_pm_cnt_read,
     .write = acpi_pm_cnt_write,