diff --git a/arch/sim/src/up_head.c b/arch/sim/src/up_head.c
index f7f5374e3ca..9ef650f7d24 100644
--- a/arch/sim/src/up_head.c
+++ b/arch/sim/src/up_head.c
@@ -96,7 +96,7 @@ int main(int argc, char **argv, char **envp)
 
   /* Restore the original terminal mode and return the exit code */
 
-  simuart_teriminate();
+  simuart_terminate();
   return g_exitcode;
 }
 
diff --git a/arch/sim/src/up_idle.c b/arch/sim/src/up_idle.c
index 2cfd5a5b8c1..7d531e32f4c 100644
--- a/arch/sim/src/up_idle.c
+++ b/arch/sim/src/up_idle.c
@@ -93,7 +93,7 @@ void up_idle(void)
    * should not matter which, however.
    */
 
-  static volatile spinlock_t lock;
+  static volatile spinlock_t lock = SP_UNLOCKED;
 
   /* The one that gets the lock is the one that executes the IDLE operations */
 
@@ -130,7 +130,6 @@ void up_idle(void)
     }
 #endif
 
-
 #ifdef CONFIG_NET_ETHERNET
   /* Run the network if enabled */
 
diff --git a/arch/sim/src/up_internal.h b/arch/sim/src/up_internal.h
index 4f723c1599d..214e337a6e8 100644
--- a/arch/sim/src/up_internal.h
+++ b/arch/sim/src/up_internal.h
@@ -237,7 +237,7 @@ void simuart_start(void);
 int simuart_putc(int ch);
 int simuart_getc(void);
 bool simuart_checkc(void);
-void simuart_teriminate(void);
+void simuart_terminate(void);
 
 /* up_uartwait.c **********************************************************/
 
diff --git a/arch/sim/src/up_simuart.c b/arch/sim/src/up_simuart.c
index 248848a2068..5e3518f3229 100644
--- a/arch/sim/src/up_simuart.c
+++ b/arch/sim/src/up_simuart.c
@@ -89,7 +89,6 @@ void simuart_wait(void);
 
 static struct termios g_cooked;
 
-
 /****************************************************************************
  * Private Functions
  ****************************************************************************/
@@ -140,12 +139,11 @@ static void *simuart_thread(void *arg)
 
       /* Check for failures (but don't do anything) */
 
-      if (nread == 1)
+      for (; nread > 0; nread--)
         {
 #ifdef CONFIG_SIM_UART_DATAPOST
           sched_lock();
 #endif
-
           /* Get the index to the next slot in the UART buffer */
 
           prev = g_uarthead;
@@ -276,7 +274,7 @@ int simuart_getc(void)
   int ch;
 
   /* Locking the scheduler should eliminate the race conditions in the
-   * unlikely case of mutliple reading threads.
+   * unlikely case of multiple reading threads.
    */
 
   sched_lock();
@@ -319,10 +317,10 @@ bool simuart_checkc(void)
 }
 
 /****************************************************************************
- * Name: simuart_teriminate
+ * Name: simuart_terminate
  ****************************************************************************/
 
-void simuart_teriminate(void)
+void simuart_terminate(void)
 {
   /* Restore the original terminal mode */