diff --git a/arch/mn10300/kernel/gdb-io-serial.c b/arch/mn10300/kernel/gdb-io-serial.c
index 9a6d4e8ebe73..11584c51acd9 100644
--- a/arch/mn10300/kernel/gdb-io-serial.c
+++ b/arch/mn10300/kernel/gdb-io-serial.c
@@ -99,6 +99,7 @@ int gdbstub_io_rx_char(unsigned char *_ch, int nonblock)
  try_again:
 	/* pull chars out of the buffer */
 	ix = gdbstub_rx_outp;
+	barrier();
 	if (ix == gdbstub_rx_inp) {
 		if (nonblock)
 			return -EAGAIN;
@@ -110,6 +111,7 @@ int gdbstub_io_rx_char(unsigned char *_ch, int nonblock)
 
 	ch = gdbstub_rx_buffer[ix++];
 	st = gdbstub_rx_buffer[ix++];
+	barrier();
 	gdbstub_rx_outp = ix & 0x00000fff;
 
 	if (st & UART_LSR_BI) {