diff --git a/include/devs.h b/include/devs.h
index 45cbc10..f381f42 100644
--- a/include/devs.h
+++ b/include/devs.h
@@ -27,7 +27,7 @@ int dev_close(id_t id);
 int dev_read(id_t id, void *data, size_t size, size_t offset);
 
 
-int dev_write(id_t id, void *data, size_t size, size_t offset);
+int dev_write(id_t id, const void *data, size_t size, size_t offset);
 
 
 #endif /* PHOENIX_DEVS_H_ */
diff --git a/include/filter.h b/include/filter.h
index e505cc2..5075d21 100644
--- a/include/filter.h
+++ b/include/filter.h
@@ -23,7 +23,7 @@ int pf_filterIn(struct pbuf *pbuf, struct netif *netif);
 int pf_filterOut(struct pbuf *pbuf, struct netif *netif);
 
 
-int pf_rulesUpdate(pfrule_array_t *array);
+int pf_rulesUpdate(const pfrule_array_t *array);
 
 
 void init_filters(void);
diff --git a/port/devs.c b/port/devs.c
index 0c3db2a..b8328ec 100644
--- a/port/devs.c
+++ b/port/devs.c
@@ -558,9 +558,9 @@ static int pf_close(void)
 }
 
 
-static int pf_write(char *data, size_t size)
+static int pf_write(const void *data, size_t size)
 {
-	pfrule_array_t *input = (pfrule_array_t *)data;
+	const pfrule_array_t *input = data;
 
 	if (input == NULL || !size || size != input->len * sizeof(pfrule_t) + sizeof(pfrule_array_t))
 		return -EINVAL;
@@ -714,7 +714,7 @@ int dev_read(id_t id, void *data, size_t size, size_t offset)
 }
 
 
-int dev_write(id_t id, void *data, size_t size, size_t offset)
+int dev_write(id_t id, const void *data, size_t size, size_t offset)
 {
 	switch (id) {
 #if LWIP_ROUTE_DEV
diff --git a/port/filter.c b/port/filter.c
index 50beb14..0110f0d 100644
--- a/port/filter.c
+++ b/port/filter.c
@@ -261,7 +261,7 @@ static int _pf_processRule(pfrule_t *rule)
 }
 
 
-int pf_rulesUpdate(pfrule_array_t *array)
+int pf_rulesUpdate(const pfrule_array_t *array)
 {
 	pfrule_t *newlist = NULL, *listhead = NULL, *newrule;
 	size_t i;
diff --git a/port/sockets.c b/port/sockets.c
index 0b7319b..204e840 100644
--- a/port/sockets.c
+++ b/port/sockets.c
@@ -1130,7 +1130,7 @@ static void socketsrv_thread(void *arg)
 	int err, sock, type;
 #if LWIP_DNS
 	struct addrinfo hint = { 0 };
-	char *node, *serv;
+	const char *node, *serv;
 #endif
 
 	port = (unsigned)arg;
diff --git a/wi-fi/lwip/main.c b/wi-fi/lwip/main.c
index bc5629c..bd42f50 100644
--- a/wi-fi/lwip/main.c
+++ b/wi-fi/lwip/main.c
@@ -426,7 +426,7 @@ static int wifi_dev_read(char *data, size_t size, off_t offset)
 }
 
 
-static int wifi_dev_write(char *data, size_t size)
+static int wifi_dev_write(const char *data, size_t size)
 {
 	if (size >= 8 && strncmp("timeout ", data, 8) == 0) {
 		wifi_ap_set_idle_timeout(data + 8, size - 8);