diff --git a/include/nuttx/irq.h b/include/nuttx/irq.h
index fb5906fa502..4d5cbb49173 100644
--- a/include/nuttx/irq.h
+++ b/include/nuttx/irq.h
@@ -78,17 +78,21 @@
 
 #if defined(CONFIG_ARCH_MINIMAL_VECTORTABLE_DYNAMIC)
 #  if defined(CONFIG_ARCH_IRQ_TO_NDX)
-#    define IRQ_TO_NDX(irq) up_irq_to_ndx(irq)
+#    define IRQ_TO_NDX(irq) \
+       ((irq) < 0 || (irq) >= NR_IRQS ? -EINVAL : up_irq_to_ndx(irq))
 #  else
-#    define IRQ_TO_NDX(irq) (g_irqmap[irq] ? g_irqmap[irq] : irq_to_ndx(irq))
+#    define IRQ_TO_NDX(irq) \
+       ((irq) < 0 || (irq) >= NR_IRQS ? -EINVAL : \
+        (g_irqmap[irq] ? g_irqmap[irq] : irq_to_ndx(irq)))
 #  endif
 #  define NDX_TO_IRQ(ndx) g_irqrevmap[ndx]
 #elif defined(CONFIG_ARCH_MINIMAL_VECTORTABLE)
 #  define IRQ_TO_NDX(irq) \
-  (g_irqmap[(irq)] < CONFIG_ARCH_NUSER_INTERRUPTS ? g_irqmap[(irq)] : -EINVAL)
+     ((irq) < 0 || (irq) >= NR_IRQS ? -EINVAL : \
+      (g_irqmap[(irq)] < CONFIG_ARCH_NUSER_INTERRUPTS ? g_irqmap[(irq)] : -EINVAL))
 #  define NDX_TO_IRQ(ndx) ndx_to_irq(ndx)
 #else
-#  define IRQ_TO_NDX(irq) (irq)
+#  define IRQ_TO_NDX(irq) ((irq) < 0 || (irq) >= NR_IRQS ? -EINVAL : (irq))
 #  define NDX_TO_IRQ(ndx) (ndx)
 #endif
 
diff --git a/sched/irq/irq_attach.c b/sched/irq/irq_attach.c
index 849f9be9fa4..5dcebc62dcf 100644
--- a/sched/irq/irq_attach.c
+++ b/sched/irq/irq_attach.c
@@ -115,14 +115,7 @@ int irq_attach(int irq, xcpt_t isr, FAR void *arg)
 {
   int ret = OK;
 #if NR_IRQS > 0
-  int ndx = -EINVAL;
-  irqstate_t flags;
-
-  if (irq >= 0 && irq < NR_IRQS)
-    {
-      ndx = IRQ_TO_NDX(irq);
-    }
-
+  int ndx = IRQ_TO_NDX(irq);
   if (ndx < 0)
     {
       ret = ndx;
@@ -134,7 +127,7 @@ int irq_attach(int irq, xcpt_t isr, FAR void *arg)
        * to the unexpected interrupt handler.
        */
 
-      flags = spin_lock_irqsave(&g_irqlock);
+      irqstate_t flags = spin_lock_irqsave(&g_irqlock);
       if (isr == NULL)
         {
           /* Disable the interrupt if we can before detaching it.  We might
diff --git a/sched/irq/irq_attach_thread.c b/sched/irq/irq_attach_thread.c
index 9e2fc5df333..2cad59a4d2d 100644
--- a/sched/irq/irq_attach_thread.c
+++ b/sched/irq/irq_attach_thread.c
@@ -155,13 +155,7 @@ int irq_attach_thread(int irq, xcpt_t isr, xcpt_t isrthread, FAR void *arg,
   char arg3[32];  /* isrthread */
   char arg4[32];  /* arg */
   pid_t pid;
-  int ndx = -EINVAL;
-
-  if (irq >= 0 && irq < NR_IRQS)
-    {
-      ndx = IRQ_TO_NDX(irq);
-    }
-
+  int ndx = IRQ_TO_NDX(irq);
   if (ndx < 0)
     {
       ret = ndx;
diff --git a/sched/irq/irq_attach_wqueue.c b/sched/irq/irq_attach_wqueue.c
index 783629b9f01..42db826e579 100644
--- a/sched/irq/irq_attach_wqueue.c
+++ b/sched/irq/irq_attach_wqueue.c
@@ -175,13 +175,7 @@ int irq_attach_wqueue(int irq, xcpt_t isr, xcpt_t isrwork,
   FAR struct irq_work_info_s *info;
   int ret = OK;
 #if NR_IRQS > 0
-  int ndx = -EINVAL;
-
-  if (irq >= 0 && irq < NR_IRQS)
-    {
-      ndx = IRQ_TO_NDX(irq);
-    }
-
+  int ndx = IRQ_TO_NDX(irq);
   if (ndx < 0)
     {
       ret = ndx;
diff --git a/sched/irq/irq_chain.c b/sched/irq/irq_chain.c
index 76c6e94b331..9b1284847de 100644
--- a/sched/irq/irq_chain.c
+++ b/sched/irq/irq_chain.c
@@ -211,23 +211,19 @@ int irqchain_attach(int ndx, xcpt_t isr, FAR void *arg)
 
 int irqchain_detach(int irq, xcpt_t isr, FAR void *arg)
 {
+  int ret = OK;
 #if NR_IRQS > 0
   FAR struct irqchain_s *prev;
   FAR struct irqchain_s *curr;
   FAR struct irqchain_s *first;
-  int ret = -EINVAL;
-
-  if ((unsigned)irq < NR_IRQS)
+  int ndx = IRQ_TO_NDX(irq);
+  if (ndx < 0)
     {
-      int ndx = IRQ_TO_NDX(irq);
-      irqstate_t flags;
-
-      if (ndx < 0)
-        {
-          return ndx;
-        }
-
-      flags = spin_lock_irqsave(&g_irqchainlock);
+      ret = ndx;
+    }
+  else
+    {
+      irqstate_t flags = spin_lock_irqsave(&g_irqchainlock);
 
       if (g_irqvector[ndx].handler == irqchain_dispatch)
         {
@@ -276,9 +272,7 @@ int irqchain_detach(int irq, xcpt_t isr, FAR void *arg)
           ret = irq_detach(irq);
         }
     }
+#endif
 
   return ret;
-#else
-  return OK;
-#endif
 }