diff --git a/sys/x86/x86/mp_x86.c b/sys/x86/x86/mp_x86.c
index 4b8a6931686c..1d3c7ed85ab2 100644
--- a/sys/x86/x86/mp_x86.c
+++ b/sys/x86/x86/mp_x86.c
@@ -1088,8 +1088,8 @@ smp_after_idle_runnable(void *arg __unused)
 
 	for (cpu = 1; cpu < mp_ncpus; cpu++) {
 		idle_td = pcpu_find(cpu)->pc_idlethread;
-		while (idle_td->td_lastcpu == NOCPU &&
-		    idle_td->td_oncpu == NOCPU)
+		while (atomic_load_int(&idle_td->td_lastcpu) == NOCPU &&
+		    atomic_load_int(&idle_td->td_oncpu) == NOCPU)
 			cpu_spinwait();
 		kmem_free((vm_offset_t)bootstacks[cpu], kstack_pages *
 		    PAGE_SIZE);