diff --git a/mm/mm_heap/mm_malloc.c b/mm/mm_heap/mm_malloc.c
index 6d39ef2b32..c8c12a974d 100644
--- a/mm/mm_heap/mm_malloc.c
+++ b/mm/mm_heap/mm_malloc.c
@@ -47,12 +47,12 @@ static void free_delaylist(FAR struct mm_heap_s *heap)
 
   /* Move the delay list to local */
 
-  flags = enter_critical_section();
+  flags = spin_lock_irqsave(NULL);
 
   tmp = heap->mm_delaylist[up_cpu_index()];
   heap->mm_delaylist[up_cpu_index()] = NULL;
 
-  leave_critical_section(flags);
+  spin_unlock_irqrestore(NULL, flags);
 
   /* Test if the delayed is empty */
 
diff --git a/sched/timer/timer_create.c b/sched/timer/timer_create.c
index e9bd4dcf4b..315d771d2b 100644
--- a/sched/timer/timer_create.c
+++ b/sched/timer/timer_create.c
@@ -33,6 +33,7 @@
 #include <nuttx/irq.h>
 #include <nuttx/wdog.h>
 #include <nuttx/kmalloc.h>
+#include <nuttx/spinlock.h>
 
 #include "timer/timer.h"
 
@@ -59,10 +60,10 @@ static FAR struct posix_timer_s *timer_allocate(void)
   /* Try to get a preallocated timer from the free list */
 
 #if CONFIG_PREALLOC_TIMERS > 0
-  flags = enter_critical_section();
+  flags = spin_lock_irqsave(NULL);
   ret   = (FAR struct posix_timer_s *)
     sq_remfirst((FAR sq_queue_t *)&g_freetimers);
-  leave_critical_section(flags);
+  spin_unlock_irqrestore(NULL, flags);
 
   /* Did we get one? */
 
@@ -91,9 +92,9 @@ static FAR struct posix_timer_s *timer_allocate(void)
 
       /* And add it to the end of the list of allocated timers */
 
-      flags = enter_critical_section();
+      flags = spin_lock_irqsave(NULL);
       sq_addlast((FAR sq_entry_t *)ret, (FAR sq_queue_t *)&g_alloctimers);
-      leave_critical_section(flags);
+      spin_unlock_irqrestore(NULL, flags);
     }
 
   return ret;
diff --git a/sched/timer/timer_release.c b/sched/timer/timer_release.c
index bfd85b6564..0b922f0f87 100644
--- a/sched/timer/timer_release.c
+++ b/sched/timer/timer_release.c
@@ -29,6 +29,7 @@
 #include <nuttx/irq.h>
 #include <nuttx/queue.h>
 #include <nuttx/kmalloc.h>
+#include <nuttx/spinlock.h>
 
 #include "timer/timer.h"
 
@@ -54,7 +55,7 @@ static inline void timer_free(struct posix_timer_s *timer)
 
   /* Remove the timer from the allocated list */
 
-  flags = enter_critical_section();
+  flags = spin_lock_irqsave(NULL);
   sq_rem((FAR sq_entry_t *)timer, (FAR sq_queue_t *)&g_alloctimers);
 
   /* Return it to the free list if it is one of the preallocated timers */
@@ -63,14 +64,14 @@ static inline void timer_free(struct posix_timer_s *timer)
   if ((timer->pt_flags & PT_FLAGS_PREALLOCATED) != 0)
     {
       sq_addlast((FAR sq_entry_t *)timer, (FAR sq_queue_t *)&g_freetimers);
-      leave_critical_section(flags);
+      spin_unlock_irqrestore(NULL, flags);
     }
   else
 #endif
     {
       /* Otherwise, return it to the heap */
 
-      leave_critical_section(flags);
+      spin_unlock_irqrestore(NULL, flags);
       kmm_free(timer);
     }
 }