diff --git a/sched/irq/irq_attach.c b/sched/irq/irq_attach.c
index 3f1e534bf49..849f9be9fa4 100644
--- a/sched/irq/irq_attach.c
+++ b/sched/irq/irq_attach.c
@@ -113,19 +113,22 @@ int ndx_to_irq(int ndx)
 
 int irq_attach(int irq, xcpt_t isr, FAR void *arg)
 {
+  int ret = OK;
 #if NR_IRQS > 0
-  int ret = -EINVAL;
+  int ndx = -EINVAL;
+  irqstate_t flags;
 
   if (irq >= 0 && irq < NR_IRQS)
     {
-      int ndx = IRQ_TO_NDX(irq);
-      irqstate_t flags;
-
-      if (ndx < 0)
-        {
-          return ndx;
-        }
+      ndx = IRQ_TO_NDX(irq);
+    }
 
+  if (ndx < 0)
+    {
+      ret = ndx;
+    }
+  else
+    {
       /* If the new ISR is NULL, then the ISR is being detached.
        * In this case, disable the ISR and direct any interrupts
        * to the unexpected interrupt handler.
@@ -166,26 +169,24 @@ int irq_attach(int irq, xcpt_t isr, FAR void *arg)
         {
           ret = irqchain_attach(ndx, isr, arg);
           spin_unlock_irqrestore(&g_irqlock, flags);
-          return ret;
         }
+      else
 #endif
+        {
+          /* Save the new ISR and its argument in the table. */
 
-      /* Save the new ISR and its argument in the table. */
+          g_irqvector[ndx].handler = isr;
+          g_irqvector[ndx].arg     = arg;
+    #ifdef CONFIG_SCHED_IRQMONITOR
+          g_irqvector[ndx].start   = clock_systime_ticks();
+          g_irqvector[ndx].time    = 0;
+          g_irqvector[ndx].count   = 0;
+    #endif
 
-      g_irqvector[ndx].handler = isr;
-      g_irqvector[ndx].arg     = arg;
-#ifdef CONFIG_SCHED_IRQMONITOR
-      g_irqvector[ndx].start   = clock_systime_ticks();
-      g_irqvector[ndx].time    = 0;
-      g_irqvector[ndx].count   = 0;
-#endif
-
-      spin_unlock_irqrestore(&g_irqlock, flags);
-      ret = OK;
+          spin_unlock_irqrestore(&g_irqlock, flags);
+        }
     }
+#endif  /* NR_IRQS */
 
   return ret;
-#else
-  return OK;
-#endif
 }
diff --git a/sched/irq/irq_attach_thread.c b/sched/irq/irq_attach_thread.c
index ef57c7f1510..9e2fc5df333 100644
--- a/sched/irq/irq_attach_thread.c
+++ b/sched/irq/irq_attach_thread.c
@@ -145,6 +145,7 @@ static int isr_thread_main(int argc, FAR char *argv[])
 int irq_attach_thread(int irq, xcpt_t isr, xcpt_t isrthread, FAR void *arg,
                       int priority, int stack_size)
 {
+  int ret = OK;
 #if NR_IRQS > 0
   static pid_t irq_thread_pid[NR_IRQS];
 
@@ -154,56 +155,52 @@ 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;
+  int ndx = -EINVAL;
 
-  if (irq < 0 || irq >= NR_IRQS)
+  if (irq >= 0 && irq < NR_IRQS)
     {
-      return -EINVAL;
+      ndx = IRQ_TO_NDX(irq);
     }
 
-  ndx = IRQ_TO_NDX(irq);
   if (ndx < 0)
     {
-      return ndx;
+      ret = ndx;
     }
-
-  /* If the isrthread is NULL, then the ISR is being detached. */
-
-  if (isrthread == NULL)
+  else if(isrthread == NULL)
     {
+      /* If the isrthread is NULL, then the ISR is being detached. */
+
       irq_detach(irq);
       DEBUGASSERT(irq_thread_pid[ndx] != 0);
       kthread_delete(irq_thread_pid[ndx]);
       irq_thread_pid[ndx] = 0;
-
-      return OK;
     }
-
-  if (irq_thread_pid[ndx] != 0)
+  else if(irq_thread_pid[ndx] != 0)
     {
-      return -EINVAL;
+      ret = -EINVAL;
     }
-
-  snprintf(arg1, sizeof(arg1), "%d", irq);
-  snprintf(arg2, sizeof(arg2), "%p", isr);
-  snprintf(arg3, sizeof(arg3), "%p", isrthread);
-  snprintf(arg4, sizeof(arg4), "%p", arg);
-  argv[0] = arg1;
-  argv[1] = arg2;
-  argv[2] = arg3;
-  argv[3] = arg4;
-  argv[4] = NULL;
-
-  pid = kthread_create("isr_thread", priority, stack_size,
-                        isr_thread_main, argv);
-  if (pid < 0)
+  else
     {
-      return pid;
+      snprintf(arg1, sizeof(arg1), "%d", irq);
+      snprintf(arg2, sizeof(arg2), "%p", isr);
+      snprintf(arg3, sizeof(arg3), "%p", isrthread);
+      snprintf(arg4, sizeof(arg4), "%p", arg);
+      argv[0] = arg1;
+      argv[1] = arg2;
+      argv[2] = arg3;
+      argv[3] = arg4;
+      argv[4] = NULL;
+
+      pid = kthread_create("isr_thread", priority, stack_size,
+                            isr_thread_main, argv);
+      if (pid < 0)
+        {
+          ret = pid;
+        }
+
+      irq_thread_pid[ndx] = pid;
     }
-
-  irq_thread_pid[ndx] = pid;
-
 #endif /* NR_IRQS */
 
-  return OK;
+  return ret;
 }
diff --git a/sched/irq/irq_attach_wqueue.c b/sched/irq/irq_attach_wqueue.c
index 10fdaf7c7bd..9ca431e7011 100644
--- a/sched/irq/irq_attach_wqueue.c
+++ b/sched/irq/irq_attach_wqueue.c
@@ -75,7 +75,7 @@ inline_function FAR struct kwork_wqueue_s *irq_get_wqueue(int priority)
   static mutex_t irq_wqueue_lock = NXMUTEX_INITIALIZER;
   static FAR struct kwork_wqueue_s *irq_wqueue[CONFIG_IRQ_NWORKS];
 
-  FAR struct kwork_wqueue_s *queue;
+  FAR struct kwork_wqueue_s *queue = NULL;
   int wqueue_priority;
   int i;
 
@@ -89,17 +89,22 @@ inline_function FAR struct kwork_wqueue_s *irq_get_wqueue(int priority)
       if (wqueue_priority == priority)
         {
           nxmutex_unlock(&irq_wqueue_lock);
-          return irq_wqueue[i];
+          queue = irq_wqueue[i];
+          break;
         }
     }
 
   DEBUGASSERT(i < CONFIG_IRQ_NWORKS);
 
-  queue = work_queue_create("isrwork", priority, irq_work_stack[i],
-                            CONFIG_IRQ_WORK_STACKSIZE, 1);
+  if (queue == NULL)
+    {
+      queue = work_queue_create("isrwork", priority, irq_work_stack[i],
+                                CONFIG_IRQ_WORK_STACKSIZE, 1);
+
+      irq_wqueue[i] = queue;
+      nxmutex_unlock(&irq_wqueue_lock);
+    }
 
-  irq_wqueue[i] = queue;
-  nxmutex_unlock(&irq_wqueue_lock);
   return queue;
 }
 
@@ -170,47 +175,48 @@ int irq_attach_wqueue(int irq, xcpt_t isr, xcpt_t isrwork,
 #endif
 
   FAR struct irq_work_info_s *info;
-
+  int ret = OK;
 #if NR_IRQS > 0
-  int ndx;
+  int ndx = -EINVAL;
 
-  if (irq < 0 || irq >= NR_IRQS)
+  if (irq >= 0 && irq < NR_IRQS)
     {
-      return -EINVAL;
+      ndx = IRQ_TO_NDX(irq);
     }
 
-  ndx = IRQ_TO_NDX(irq);
   if (ndx < 0)
     {
-      return ndx;
+      ret = ndx;
     }
-
-  /* If the isrwork is NULL, then the ISR is being detached. */
-
-  info = &irq_work_vector[ndx];
-
-  if (isrwork == NULL)
+  else
     {
-      irq_detach(irq);
-      info->isrwork = NULL;
-      info->handler = NULL;
-      info->arg     = NULL;
-      info->wqueue  = NULL;
-      return OK;
-    }
+      /* If the isrwork is NULL, then the ISR is being detached. */
 
-  info->isrwork = isrwork;
-  info->handler = isr;
-  info->arg     = arg;
-  info->irq     = irq;
-  if (info->wqueue == NULL)
-    {
-      info->wqueue = irq_get_wqueue(priority);
-    }
+      info = &irq_work_vector[ndx];
 
-  irq_attach(irq, irq_default_handler, info);
+      if (isrwork == NULL)
+        {
+          irq_detach(irq);
+          info->isrwork = NULL;
+          info->handler = NULL;
+          info->arg     = NULL;
+          info->wqueue  = NULL;
+        }
+      else
+        {
+          info->isrwork = isrwork;
+          info->handler = isr;
+          info->arg     = arg;
+          info->irq     = irq;
+          if (info->wqueue == NULL)
+            {
+              info->wqueue = irq_get_wqueue(priority);
+            }
+
+          irq_attach(irq, irq_default_handler, info);
+        }
+    }
 #endif /* NR_IRQS */
 
-  return OK;
+  return ret;
 }
-