diff --git a/sched/irq/irq_chain.c b/sched/irq/irq_chain.c
index cb292ac45d2..fd9bd4ba8ad 100644
--- a/sched/irq/irq_chain.c
+++ b/sched/irq/irq_chain.c
@@ -154,7 +154,7 @@ int irqchain_attach(int ndx, xcpt_t isr, FAR void *arg)
     {
       if (g_irqvector[ndx].handler != irqchain_dispatch)
         {
-          if (sq_count(&g_irqchainfreelist) < 2)
+          if (sq_count(&g_irqchainfreelist) < 2u)
             {
               spin_unlock_irqrestore(&g_irqchainlock, flags);
               return -ENOMEM;