diff --git a/mm/mm_heap/mm_free.c b/mm/mm_heap/mm_free.c
index 4700aeeede..7716c720ce 100644
--- a/mm/mm_heap/mm_free.c
+++ b/mm/mm_heap/mm_free.c
@@ -45,12 +45,12 @@ static void add_delaylist(FAR struct mm_heap_s *heap, FAR void *mem)
 
   /* Delay the deallocation until a more appropriate time. */
 
-  flags = enter_critical_section();
+  flags = spin_lock_irqsave(NULL);
 
   tmp->flink = heap->mm_delaylist[up_cpu_index()];
   heap->mm_delaylist[up_cpu_index()] = tmp;
 
-  leave_critical_section(flags);
+  spin_unlock_irqrestore(NULL, flags);
 #endif
 }