diff --git a/mm/mempool/mempool.c b/mm/mempool/mempool.c
index d1ee35caf2..10186c2aa9 100644
--- a/mm/mempool/mempool.c
+++ b/mm/mempool/mempool.c
@@ -317,7 +317,7 @@ out_with_lock:
 
 void mempool_free(FAR struct mempool_s *pool, FAR void *blk)
 {
-  irqstate_t flags;
+  irqstate_t flags = spin_lock_irqsave(&pool->lock);
 #if CONFIG_MM_BACKTRACE >= 0
   size_t blocksize =  ALIGN_UP(pool->blocksize +
                                sizeof(struct mempool_backtrace_s),
@@ -332,8 +332,6 @@ void mempool_free(FAR struct mempool_s *pool, FAR void *blk)
   pool->nalloc--;
 #endif
 
-  flags = spin_lock_irqsave(&pool->lock);
-
   if (pool->interruptsize > blocksize)
     {
       if ((FAR char *)blk >= pool->ibase &&