diff --git a/boards/wsn430-common/wsn430-uart0.c b/boards/wsn430-common/wsn430-uart0.c
index 9a82348ad2..7161d431dc 100644
--- a/boards/wsn430-common/wsn430-uart0.c
+++ b/boards/wsn430-common/wsn430-uart0.c
@@ -35,7 +35,7 @@ void usart0irq(void);
  * \brief the interrupt function
  */
 interrupt(USART0RX_VECTOR) usart0irq(void) {
-    int dummy = 0;
+    volatile int dummy = 0;
     /* Check status register for receive errors. */
     if(U0RCTL & RXERR) {
         if (U0RCTL & FE) {
@@ -52,12 +52,13 @@ interrupt(USART0RX_VECTOR) usart0irq(void) {
         }
         /* Clear error flags by forcing a dummy read. */
         dummy = U0RXBUF;
+        (void)dummy;
     }
 #ifdef MODULE_UART0
     else if (uart0_handler_pid != KERNEL_PID_UNDEF) {
-                dummy = U0RXBUF;
-                uart0_handle_incoming(dummy);
-                uart0_notify_thread();
-            }
+        dummy = U0RXBUF;
+        uart0_handle_incoming(dummy);
+        uart0_notify_thread();
+    }
 #endif
 }