diff --git a/ports/unix/include/netif/sio.h b/ports/unix/include/netif/sio.h
index bbe6f3e..c1e8408 100644
--- a/ports/unix/include/netif/sio.h
+++ b/ports/unix/include/netif/sio.h
@@ -78,5 +78,29 @@ sio_status_t * sio_open( int devnum );
 */
 void sio_change_baud( sioBaudrates baud, sio_status_t * siostat );
 
+#if PPP_SUPPORT
+/**
+*	Write buffer to serial port
+* @param 	siostat siostatus struct, contains sio instance data, given by sio_open
+* @param 	buf	output buffer
+* @param 	size	output buffer size
+*/
+u32_t sio_write(sio_status_t * siostat, u8_t *buf, u32_t size);
+
+/**
+*	Read buffer from serial port
+* @param 	siostat siostatus struct, contains sio instance data, given by sio_open
+* @param 	buf	input buffer
+* @param 	size	input buffer size
+*/
+u32_t sio_read(sio_status_t * siostat, u8_t *buf, u32_t size);
+
+/**
+*	Flush serial port input buffer
+* @param 	siostat siostatus struct, contains sio instance data, given by sio_open
+*/
+void sio_read_abort(sio_status_t * siostat);
+#endif /* PPP_SUPPORT */
+
 #endif
 
diff --git a/ports/unix/netif/sio.c b/ports/unix/netif/sio.c
index fbc80a2..31476ea 100644
--- a/ports/unix/netif/sio.c
+++ b/ports/unix/netif/sio.c
@@ -99,6 +99,7 @@ static int sio_init( char * device, int devnum, sio_status_t * siostat )
 #endif
 	int fd;
 	LWIP_UNUSED_ARG(siostat);
+	LWIP_UNUSED_ARG(devnum);
 
 	/* open the device to be non-blocking (read will return immediately) */
 	fd = open( device, O_RDWR | O_NOCTTY | O_NONBLOCK );
@@ -278,6 +279,7 @@ u32_t sio_read(sio_status_t * siostat, u8_t *buf, u32_t size)
 
 void sio_read_abort(sio_status_t * siostat)
 {
+    LWIP_UNUSED_ARG(siostat);
     printf("sio_read_abort: not yet implemented for unix\n");
 }
 #endif /* PPP_SUPPORT */
diff --git a/ports/unix/sys_arch.c b/ports/unix/sys_arch.c
index 9bb1f59..3ccc4ad 100644
--- a/ports/unix/sys_arch.c
+++ b/ports/unix/sys_arch.c
@@ -580,18 +580,3 @@ sys_jiffies(void)
     usec /= 1000000L / HZ;
     return HZ * sec + usec;
 }
-
-#if PPP_DEBUG
-
-#include <stdarg.h>
-
-void ppp_trace(int level, const char *format, ...)
-{
-    va_list args;
-
-    (void)level;
-    va_start(args, format);
-    vprintf(format, args);
-    va_end(args);
-}
-#endif