diff --git a/libcpu/arm/s3c24x0/serial.h b/libcpu/arm/s3c24x0/serial.h
index 2869e566707a4eb465b717abadb6aa6e909d51e6..1015f2a9357c1f7be048c8061d10429b4e68580c 100644
--- a/libcpu/arm/s3c24x0/serial.h
+++ b/libcpu/arm/s3c24x0/serial.h
@@ -27,17 +27,17 @@ struct serial_int_tx
 
 typedef struct uartport
 {
-	rt_uint32_t ulcon;
-	rt_uint32_t ucon;
-	rt_uint32_t ufcon;
-	rt_uint32_t umcon;
-	rt_uint32_t ustat;
-	rt_uint32_t urxb;
-	rt_uint32_t ufstat;
-	rt_uint32_t umstat;
-	rt_uint32_t utxh;	
-	rt_uint32_t urxh;	
-	rt_uint32_t ubrd;
+	volatile rt_uint32_t ulcon;
+	volatile rt_uint32_t ucon;
+	volatile rt_uint32_t ufcon;
+	volatile rt_uint32_t umcon;
+	volatile rt_uint32_t ustat;
+	volatile rt_uint32_t urxb;
+	volatile rt_uint32_t ufstat;
+	volatile rt_uint32_t umstat;
+	volatile rt_uint32_t utxh;	
+	volatile rt_uint32_t urxh;	
+	volatile rt_uint32_t ubrd;
 }uartport;
 
 struct serial_device