diff --git a/drivers/serial/serial_s5p.c b/drivers/serial/serial_s5p.c
index 9747db3..e0d4e80 100644
--- a/drivers/serial/serial_s5p.c
+++ b/drivers/serial/serial_s5p.c
@@ -133,7 +133,7 @@
 			return 0;
 	}
 
-	return (int)(readl(&uart->urxh) & 0xff);
+	return (int)(readb(&uart->urxh) & 0xff);
 }
 
 /*
@@ -149,7 +149,7 @@
 			return;
 	}
 
-	writel(c, &uart->utxh);
+	writeb(c, &uart->utxh);
 
 	/* If \n, also do \r */
 	if (c == '\n')