diff --git a/os/dev/slip.h b/os/dev/slip.h
index ddc8c7e74..759de1a46 100644
--- a/os/dev/slip.h
+++ b/os/dev/slip.h
@@ -80,7 +80,7 @@ void slip_set_input_callback(void (*callback)(void));
  * These machine dependent functions and an interrupt service routine
  * must be provided externally (slip_arch.c).
  */
-void slip_arch_init(unsigned long ubr);
+void slip_arch_init(void);
 void slip_arch_writeb(unsigned char c);
 
 #endif /* SLIP_H_ */
diff --git a/tools/sky/uip6-bridge/dev/slip.h b/tools/sky/uip6-bridge/dev/slip.h
index 099c35111..d164ee97c 100644
--- a/tools/sky/uip6-bridge/dev/slip.h
+++ b/tools/sky/uip6-bridge/dev/slip.h
@@ -86,7 +86,7 @@ void slip_set_tcpip_input_callback(void (*callback)(void));
  * These machine dependent functions and an interrupt service routine
  * must be provided externally (slip_arch.c).
  */
-void slip_arch_init(unsigned long ubr);
+void slip_arch_init(void);
 void slip_arch_writeb(unsigned char c);
 
 #endif /* SLIP_H_ */