diff --git a/rtl837x_port.c b/rtl837x_port.c
index aa91a7a..4c12a51 100644
--- a/rtl837x_port.c
+++ b/rtl837x_port.c
@@ -463,14 +463,14 @@ void port_stats_print(void) __banked
 }
 
 
-void port_isolate(register uint8_t port, __xdata uint16_t pmask)
+void port_isolate(register uint8_t port, __xdata uint16_t pmask) __banked
 {
 	if (port <= machine.max_port)
 		REG_SET(RTL837X_PORT_ISOLATION_BASE + (port << 2), pmask);
 }
 
 
-uint16_t port_isolation_get(register uint8_t port)
+uint16_t port_isolation_get(register uint8_t port) __banked
 {
 	if (port > machine.max_port)
 		return 0;
diff --git a/rtl837x_port.h b/rtl837x_port.h
index 20132fb..9be1680 100644
--- a/rtl837x_port.h
+++ b/rtl837x_port.h
@@ -61,4 +61,7 @@ void port_eee_status(uint8_t port) __banked;
 void print_port_ingress_filter_mode(vlan_ingress_mode_t mode) __banked;
 bool port_ingress_vlan_filter_set(__xdata uint8_t port, __xdata bool enabled) __banked;
 bool port_ingress_vlan_filter_get(__xdata uint8_t port) __banked;
+void port_isolate(register uint8_t port, __xdata uint16_t pmask) __banked;
+uint16_t port_isolation_get(register uint8_t port) __banked;
+
 #endif