diff --git a/src/daemon.c b/src/daemon.c
index 1f5000837..c35381228 100644
--- a/src/daemon.c
+++ b/src/daemon.c
@@ -97,11 +97,11 @@ typedef struct {
 #pragma mark prototypes
 static void dummy_bluetooth_status_handler(BLUETOOTH_STATE state);
 static client_state_t * client_for_connection(connection_t *connection);
-static int              clients_require_power_on();
-static int              clients_require_discoverable();
-static void              clients_clear_power_request();
-static void start_power_off_timer();
-static void stop_power_off_timer();
+static int              clients_require_power_on(void);
+static int              clients_require_discoverable(void);
+static void              clients_clear_power_request(void);
+static void start_power_off_timer(void);
+static void stop_power_off_timer(void);
 
 #pragma mark globals
 static hci_transport_t * transport;
@@ -121,7 +121,7 @@ static void dummy_bluetooth_status_handler(BLUETOOTH_STATE state){
     log_dbg("Bluetooth status: %u\n", state);
 };
 
-static void daemon_no_connections_timeout(){
+static void daemon_no_connections_timeout(void){
     if (clients_require_power_on()) return;    // false alarm :)
     log_dbg("No active client connection for %u seconds -> POWER OFF\n", DAEMON_NO_ACTIVE_CLIENT_TIMEOUT/1000);
     hci_power_control(HCI_POWER_OFF);
@@ -364,7 +364,7 @@ static int daemon_client_handler(connection_t *connection, uint16_t packet_type,
 // local cache used to manage UI status
 static HCI_STATE hci_state = HCI_STATE_OFF;
 static int num_connections = 0;
-static void update_ui_status(){
+static void update_ui_status(void){
     if (hci_state != HCI_STATE_WORKING) {
         bluetooth_status_handler(BLUETOOTH_OFF);
     } else {
@@ -611,7 +611,7 @@ int main (int argc,  char * const * argv){
 
 #define USE_POWER_OFF_TIMER
 
-static void stop_power_off_timer(){
+static void stop_power_off_timer(void){
 #ifdef USE_POWER_OFF_TIMER
     if (timeout_active) {
         run_loop_remove_timer(&timeout);
@@ -620,7 +620,7 @@ static void stop_power_off_timer(){
 #endif
 }
 
-static void start_power_off_timer(){
+static void start_power_off_timer(void){
 #ifdef USE_POWER_OFF_TIMER    
     stop_power_off_timer();
     run_loop_set_timer(&timeout, DAEMON_NO_ACTIVE_CLIENT_TIMEOUT);
@@ -645,7 +645,7 @@ static client_state_t * client_for_connection(connection_t *connection) {
     return NULL;
 }
 
-static void clients_clear_power_request(){
+static void clients_clear_power_request(void){
     linked_item_t *it;
     for (it = (linked_item_t *) clients; it ; it = it->next){
         client_state_t * client_state = (client_state_t *) it;
@@ -653,7 +653,7 @@ static void clients_clear_power_request(){
     }
 }
 
-static int clients_require_power_on(){
+static int clients_require_power_on(void){
 
     if (global_enable) return 1;
 
@@ -667,7 +667,7 @@ static int clients_require_power_on(){
     return 0;
 }
 
-static int clients_require_discoverable(){
+static int clients_require_discoverable(void){
     linked_item_t *it;
     for (it = (linked_item_t *) clients; it ; it = it->next){
         client_state_t * client_state = (client_state_t *) it;
diff --git a/src/hci.c b/src/hci.c
index 142bcc42d..0f6652bfd 100644
--- a/src/hci.c
+++ b/src/hci.c
@@ -164,7 +164,7 @@ void hci_drop_link_key_for_bd_addr(bd_addr_t *addr){
 /**
  * count connections
  */
-static int nr_hci_connections(){
+static int nr_hci_connections(void){
     int count = 0;
     linked_item_t *it;
     for (it = (linked_item_t *) hci_stack.connections; it ; it = it->next, count++);
@@ -585,7 +585,7 @@ void hci_close(){
 // HCI_STATE_SLEEPING,    off/sleep   close
 // HCI_STATE_FALLING_ASLEEP  on       open
 
-static int hci_power_control_on(){
+static int hci_power_control_on(void){
     
     // power on
     int err = 0;
@@ -611,7 +611,7 @@ static int hci_power_control_on(){
     return 0;
 }
 
-static void hci_power_control_off(){
+static void hci_power_control_off(void){
     
     log_dbg("hci_power_control_off\n");
 
@@ -630,7 +630,7 @@ static void hci_power_control_off(){
     hci_stack.state = HCI_STATE_OFF;
 }
 
-static void hci_power_control_sleep(){
+static void hci_power_control_sleep(void){
     
     log_dbg("hci_power_control_sleep\n");
     
@@ -649,7 +649,7 @@ static void hci_power_control_sleep(){
     hci_stack.state = HCI_STATE_SLEEPING;
 }
 
-static int hci_power_control_wake(){
+static int hci_power_control_wake(void){
     
     log_dbg("hci_power_control_wake\n");
 
diff --git a/src/hci_dump.h b/src/hci_dump.h
index 7b964ed9a..06cd6c6fe 100644
--- a/src/hci_dump.h
+++ b/src/hci_dump.h
@@ -48,4 +48,4 @@ typedef enum {
 void hci_dump_open(char *filename, hci_dump_format_t format);
 void hci_dump_set_max_packets(int packets); // -1 for unlimited
 void hci_dump_packet(uint8_t packet_type, uint8_t in, uint8_t *packet, uint16_t len);
-void hci_dump_close();
+void hci_dump_close(void);
diff --git a/src/hci_transport_h4.c b/src/hci_transport_h4.c
index bc9f54650..ca1112ea3 100644
--- a/src/hci_transport_h4.c
+++ b/src/hci_transport_h4.c
@@ -192,7 +192,7 @@ static int    h4_open(void *transport_config){
     return 0;
 }
 
-static int    h4_close(){
+static int    h4_close(void){
     // first remove run loop handler
 	run_loop_remove_data_source(hci_transport_h4->ds);
     
@@ -231,7 +231,7 @@ static void   h4_register_packet_handler(void (*handler)(uint8_t packet_type, ui
     packet_handler = handler;
 }
 
-static void   h4_deliver_packet(){
+static void   h4_deliver_packet(void){
     if (read_pos < 3) return; // sanity check
     hci_dump_packet( hci_packet[0], 1, &hci_packet[1], read_pos-1);
     packet_handler(hci_packet[0], &hci_packet[1], read_pos-1);
@@ -241,7 +241,7 @@ static void   h4_deliver_packet(){
     bytes_to_read = 1;
 }
 
-static void h4_statemachine(){
+static void h4_statemachine(void){
     switch (h4_state) {
             
         case H4_W4_PACKET_TYPE:
@@ -359,7 +359,7 @@ static void *h4_reader(void *context){
 }
 #endif
 
-static const char * h4_get_transport_name(){
+static const char * h4_get_transport_name(void){
     return "H4";
 }
 
diff --git a/src/l2cap.c b/src/l2cap.c
index bdf7432bb..c1348d97b 100644
--- a/src/l2cap.c
+++ b/src/l2cap.c
@@ -149,7 +149,7 @@ void l2cap_emit_credits(l2cap_channel_t *channel, uint8_t credits) {
     l2cap_dispatch(channel, HCI_EVENT_PACKET, event, sizeof(event));
 }
 
-void l2cap_hand_out_credits(){
+void l2cap_hand_out_credits(void){
     linked_item_t *it;
     for (it = (linked_item_t *) l2cap_channels; it ; it = it->next){
         if (!hci_number_free_acl_slots()) return;
diff --git a/src/remote_device_db_iphone.m b/src/remote_device_db_iphone.m
index ba12252fd..f8d4d5633 100644
--- a/src/remote_device_db_iphone.m
+++ b/src/remote_device_db_iphone.m
@@ -52,7 +52,7 @@ static NSMutableDictionary *remote_devices  = nil;
 static NSMutableDictionary *rfcomm_services = nil;
 
 // Device info
-static void db_open(){
+static void db_open(void){
 	NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
     
     // NSUserDefaults didn't work
@@ -89,7 +89,7 @@ static void db_open(){
     [pool release];
 }
 
-static void db_synchronize(){
+static void db_synchronize(void){
     log_dbg("stored prefs for %u devices\n", (unsigned int) [remote_devices count]);
     
     // 3 different ways
@@ -106,7 +106,7 @@ static void db_synchronize(){
     // [defaults synchronize];
 }
 
-static void db_close(){ 
+static void db_close(void){ 
 	NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
 
     db_synchronize();
@@ -197,7 +197,7 @@ static int  get_name(bd_addr_t *bd_addr, device_name_t *device_name) {
 
 #pragma mark PERSISTENT RFCOMM CHANNEL ALLOCATION
 
-static int firstFreeChannelNr(){
+static int firstFreeChannelNr(void){
     BOOL channelUsed[MAX_RFCOMM_CHANNEL_NR+1];
     int i;
     for (i=0; i<=MAX_RFCOMM_CHANNEL_NR ; i++) channelUsed[i] = NO;
@@ -213,7 +213,7 @@ static int firstFreeChannelNr(){
     return -1;
 }
 
-static void deleteLeastUsed(){
+static void deleteLeastUsed(void){
     NSString * leastUsedName = nil;
     NSDate *   leastUsedDate = nil;
     for (NSString * serviceName in [rfcomm_services allKeys]){
diff --git a/src/rfcomm.c b/src/rfcomm.c
index 828406019..d258268ff 100644
--- a/src/rfcomm.c
+++ b/src/rfcomm.c
@@ -261,7 +261,7 @@ static int rfcomm_multiplexer_has_channels(rfcomm_multiplexer_t * multiplexer){
     return 0;
 }
 
-static void rfcomm_dump_channels(){
+static void rfcomm_dump_channels(void){
     linked_item_t * it;
     int channels = 0;
     for (it = (linked_item_t *) rfcomm_channels; it ; it = it->next){
@@ -544,7 +544,7 @@ static void rfcomm_emit_service_registered(void *connection, uint8_t status, uin
 	(*app_packet_handler)(connection, HCI_EVENT_PACKET, 0, (uint8_t *) event, sizeof(event));
 }
 
-static void rfcomm_hand_out_credits(){
+static void rfcomm_hand_out_credits(void){
     linked_item_t * it;
     for (it = (linked_item_t *) rfcomm_channels; it ; it = it->next){
         rfcomm_channel_t * channel = (rfcomm_channel_t *) it;
@@ -1250,7 +1250,7 @@ void rfcomm_close_connection(void *connection){
 
 #pragma mark RFCOMM BTstack API
 
-void rfcomm_init(){
+void rfcomm_init(void){
     rfcomm_client_cid_generator = 0;
     rfcomm_multiplexers = NULL;
     rfcomm_services     = NULL;
diff --git a/src/rfcomm.h b/src/rfcomm.h
index 9de0865ec..d8c990db7 100644
--- a/src/rfcomm.h
+++ b/src/rfcomm.h
@@ -38,7 +38,7 @@
 
 #include <stdint.h>
 
-void rfcomm_init();
+void rfcomm_init(void);
 
 // register packet handler
 void rfcomm_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
diff --git a/src/sdp.c b/src/sdp.c
index 4518a5f26..5f5a5bb70 100644
--- a/src/sdp.c
+++ b/src/sdp.c
@@ -109,7 +109,7 @@ service_record_item_t * sdp_get_record_for_handle(uint32_t handle){
 }
 
 // get next free, unregistered service record handle
-uint32_t sdp_create_service_record_handle(){
+uint32_t sdp_create_service_record_handle(void){
     uint32_t handle = 0;
     do {
         handle = sdp_next_service_record_handle++;
diff --git a/src/sdp.h b/src/sdp.h
index f34ea3518..ede511c6e 100644
--- a/src/sdp.h
+++ b/src/sdp.h
@@ -60,7 +60,7 @@ typedef struct {
 } service_record_item_t;
 
 
-void sdp_init();
+void sdp_init(void);
 
 void sdp_register_packet_handler(void (*handler)(void * connection, uint8_t packet_type,
                                                  uint16_t channel, uint8_t *packet, uint16_t size));
@@ -86,5 +86,5 @@ void sdp_unregister_service_internal(void *connection, uint32_t service_record_h
 void sdp_unregister_services_for_connection(void *connection);
 
 //
-void sdp_test();
+void sdp_test(void);