diff --git a/arch/arm/src/max326xx/max32660/max32660_wdt.c b/arch/arm/src/max326xx/max32660/max32660_wdt.c
index c58a82020ad..ab2f117366a 100644
--- a/arch/arm/src/max326xx/max32660/max32660_wdt.c
+++ b/arch/arm/src/max326xx/max32660/max32660_wdt.c
@@ -83,6 +83,7 @@ struct max326_wdt_lowerhalf_s
   uint8_t exp;                      /* log12(Reset time period) */
   xcpt_t handler;                   /* User interrupt handler */
   clock_t lastping;                 /* Time of last WDT reset */
+  spinlock_t lock;                  /* Spinlock */
 };
 
 /****************************************************************************
@@ -360,7 +361,7 @@ static int max326_start(struct watchdog_lowerhalf_s *lower)
 
   /* Perform the reset sequence */
 
-  flags = spin_lock_irqsave(NULL);
+  flags = spin_lock_irqsave(&priv->lock);
   max326_wdog_reset(priv);
 
   /* Enable reset or interrupt */
@@ -373,7 +374,7 @@ static int max326_start(struct watchdog_lowerhalf_s *lower)
   ctrl |= WDT0_CTRL_WDTEN;
   putreg32(ctrl, MAX326_WDT0_CTRL);
 
-  spin_unlock_irqrestore(NULL, flags);
+  spin_unlock_irqrestore(&priv->lock, flags);
   return OK;
 }
 
@@ -394,6 +395,8 @@ static int max326_start(struct watchdog_lowerhalf_s *lower)
 
 static int max326_stop(struct watchdog_lowerhalf_s *lower)
 {
+  struct max326_wdt_lowerhalf_s *priv =
+    (struct max326_wdt_lowerhalf_s *)lower;
   irqstate_t flags;
   uint32_t ctrl;
 
@@ -405,14 +408,14 @@ static int max326_stop(struct watchdog_lowerhalf_s *lower)
 
   /* Disable the watchdog timer, reset, and interrupts */
 
-  flags = spin_lock_irqsave(NULL);
+  flags = spin_lock_irqsave(&priv->lock);
   ctrl  = getreg32(MAX326_WDT0_CTRL);
   ctrl &= ~(WDT0_CTRL_WDTEN | WDT0_CTRL_INTEN | WDT0_CTRL_RSTEN);
 
   up_disable_irq(MAX326_IRQ_WDT0);
   irq_detach(MAX326_IRQ_WDT0);
 
-  spin_unlock_irqrestore(NULL, flags);
+  spin_unlock_irqrestore(&priv->lock, flags);
   return OK;
 }
 
@@ -443,9 +446,9 @@ static int max326_keepalive(struct watchdog_lowerhalf_s *lower)
 
   /* Reset WDT timer */
 
-  flags = spin_lock_irqsave(NULL);
+  flags = spin_lock_irqsave(&priv->lock);
   max326_wdog_reset(priv);
-  spin_unlock_irqrestore(NULL, flags);
+  spin_unlock_irqrestore(&priv->lock, flags);
 
   return OK;
 }
@@ -501,9 +504,9 @@ static int max326_getstatus(struct watchdog_lowerhalf_s *lower,
   status->timeleft = max326_time_left(priv);
 
   wdinfo("Status     :\n");
-  wdinfo("  flags    : %08x\n", status->flags);
-  wdinfo("  timeout  : %d\n",   status->timeout);
-  wdinfo("  timeleft : %d\n",   status->timeleft);
+  wdinfo("  flags    : %08lx\n", status->flags);
+  wdinfo("  timeout  : %ld\n",   status->timeout);
+  wdinfo("  timeleft : %ld\n",   status->timeleft);
   return OK;
 }
 
@@ -537,7 +540,7 @@ static int max326_settimeout(struct watchdog_lowerhalf_s *lower,
 
   /* Reset WDT timer */
 
-  flags = spin_lock_irqsave(NULL);
+  flags = spin_lock_irqsave(&priv->lock);
   max326_wdog_reset(priv);
 
   /* Convert the timeout value in milliseconds to time exponent used by the
@@ -559,7 +562,7 @@ static int max326_settimeout(struct watchdog_lowerhalf_s *lower,
   ctrl |= (WDT0_CTRL_INTPERIOD(exp) | WDT0_CTRL_RSTPERIOD(exp));
   putreg32(ctrl, MAX326_WDT0_CTRL);
 
-  spin_unlock_irqrestore(NULL, flags);
+  spin_unlock_irqrestore(&priv->lock, flags);
   return OK;
 }
 
@@ -587,12 +590,12 @@ static xcpt_t max326_capture(struct watchdog_lowerhalf_s *lower,
   irqstate_t flags;
   xcpt_t oldhandler;
 
-  DEBUGASSERT(priv != NULL)
+  DEBUGASSERT(priv != NULL);
   wdinfo("Handler=%p\n", handler);
 
   /* Get the old handler */
 
-  flags = spin_lock_irqsave(NULL);
+  flags = spin_lock_irqsave(&priv->lock);
   oldhandler = priv->handler;
 
   /* Save the new handler */
@@ -613,7 +616,7 @@ static xcpt_t max326_capture(struct watchdog_lowerhalf_s *lower,
       max326_int_enable(priv);
     }
 
-  spin_unlock_irqrestore(NULL, flags);
+  spin_unlock_irqrestore(&priv->lock, flags);
   return oldhandler;
 }
 
@@ -667,12 +670,12 @@ int max326_wdt_initialize(const char *devpath)
   struct max326_wdt_lowerhalf_s *priv = &g_wdtdev;
   void *handle;
 
-  wdinfo("Entry: devpath=%s, mode_sleep=%d, mode_halt=%d\n",
-         devpath, mode_sleep, mode_halt);
+  wdinfo("Entry: devpath=%s, \n", devpath);
 
   /* Initialize the driver state structure. */
 
   priv->ops = &g_wdtops;
+  spin_lock_init(&priv->lock);
 
   /* Register the watchdog driver as /dev/watchdog0 */