diff --git a/arch/x86/kernel/apic_64.c b/arch/x86/kernel/apic_64.c
index d3ec746a..eeb6983 100644
--- a/arch/x86/kernel/apic_64.c
+++ b/arch/x86/kernel/apic_64.c
@@ -1612,10 +1612,12 @@
 	cpu_set(cpu, cpu_present_map);
 }
 
+#ifdef CONFIG_X86_64
 int hard_smp_processor_id(void)
 {
 	return read_apic_id();
 }
+#endif
 
 /*
  * Power management