diff --git a/sys/dev/acpica/acpi_cpu.c b/sys/dev/acpica/acpi_cpu.c
index 5b716b7c4a0b..0d3a4acd4ee3 100644
--- a/sys/dev/acpica/acpi_cpu.c
+++ b/sys/dev/acpica/acpi_cpu.c
@@ -807,16 +807,23 @@ acpi_cpu_idle()
     uint32_t	start_time, end_time;
     int		bm_active, i, asleep;
 
-    /* Look up our CPU id and to get our softc. */
-    sc = cpu_softc[PCPU_GET(cpuid)];
-    KASSERT(sc != NULL, ("NULL softc for %d", PCPU_GET(cpuid)));
-
     /* If disabled, return immediately. */
     if (cpu_cx_count == 0) {
 	ACPI_ENABLE_IRQS();
 	return;
     }
 
+    /*
+     * Look up our CPU id to get our softc.  If it's NULL, we'll use C1
+     * since there is no ACPI processor object for this CPU.  This occurs
+     * for logical CPUs in the HTT case.
+     */
+    sc = cpu_softc[PCPU_GET(cpuid)];
+    if (sc == NULL) {
+	acpi_cpu_c1();
+	return;
+    }
+
     /* Record that a CPU is in the idle function. */
     atomic_add_int(&cpu_idle_busy, 1);