diff --git a/firmware/src_simtrace/host_communication.c b/firmware/src_simtrace/host_communication.c
index 990119fd..ab57a5d3 100644
--- a/firmware/src_simtrace/host_communication.c
+++ b/firmware/src_simtrace/host_communication.c
@@ -5,7 +5,7 @@ static bool check_for_pts = false;
 
 static struct Usart_info usart_info = {.base = USART_PHONE, .id = ID_USART_PHONE, .state = USART_RCV};
 
-void USB_write_callback(uint8_t *pArg, uint8_t status, uint32_t transferred, uint32_t remaining)
+static void USB_write_callback(uint8_t *pArg, uint8_t status, uint32_t transferred, uint32_t remaining)
 {
     if (status != USBD_STATUS_SUCCESS) {
         TRACE_ERROR("USB err status: %d(%s)\n", __FUNCTION__, status);
@@ -14,7 +14,7 @@ void USB_write_callback(uint8_t *pArg, uint8_t status, uint32_t transferred, uin
     TRACE_DEBUG("WR_CB\n");
 }
 
-int send_to_host()
+static int send_to_host()
 {
     static uint8_t msg[RING_BUFLEN];
     int ret = 0;
diff --git a/firmware/src_simtrace/phone.c b/firmware/src_simtrace/phone.c
index ab828d62..ca1dfec1 100644
--- a/firmware/src_simtrace/phone.c
+++ b/firmware/src_simtrace/phone.c
@@ -101,8 +101,8 @@ static struct Usart_info usart_info = {.base = USART_PHONE, .id = ID_USART_PHONE
 static uint8_t host_to_sim_buf[BUFLEN];
 static bool change_fidi = false;
 
-void receive_from_host( void );
-void sendResponse_to_phone( uint8_t *pArg, uint8_t status, uint32_t transferred, uint32_t remaining)
+static void receive_from_host( void );
+static void sendResponse_to_phone( uint8_t *pArg, uint8_t status, uint32_t transferred, uint32_t remaining)
 {
     if (status != USBD_STATUS_SUCCESS) {
         TRACE_ERROR("USB err status: %d (%s)\n", __FUNCTION__, status);
@@ -135,7 +135,7 @@ void sendResponse_to_phone( uint8_t *pArg, uint8_t status, uint32_t transferred,
     receive_from_host();
 }
 
-void receive_from_host()
+static void receive_from_host()
 {
     int ret;
     if ((ret = USBD_Read(PHONE_DATAOUT, &host_to_sim_buf, sizeof(host_to_sim_buf),
diff --git a/firmware/src_simtrace/simtrace_iso7816.c b/firmware/src_simtrace/simtrace_iso7816.c
index a6fabb59..086cd323 100644
--- a/firmware/src_simtrace/simtrace_iso7816.c
+++ b/firmware/src_simtrace/simtrace_iso7816.c
@@ -43,7 +43,7 @@ volatile ringbuf sim_rcv_buf = { {0}, 0, 0 };
 /*-----------------------------------------------------------------------------
  *          Interrupt routines
  *-----------------------------------------------------------------------------*/
-void Callback_PhoneRST_ISR( uint8_t *pArg, uint8_t status, uint32_t transferred, uint32_t remaining)
+static void Callback_PhoneRST_ISR( uint8_t *pArg, uint8_t status, uint32_t transferred, uint32_t remaining)
 {
     printf("rstCB\n\r");
     PIO_EnableIt( &pinPhoneRST ) ;
diff --git a/firmware/src_simtrace/usb.c b/firmware/src_simtrace/usb.c
index 9120552c..7cd4febd 100644
--- a/firmware/src_simtrace/usb.c
+++ b/firmware/src_simtrace/usb.c
@@ -149,7 +149,7 @@ enum strDescNum {
 };
 
 /** List of string descriptors used by the device */
-const unsigned char *stringDescriptors[] = {
+static const unsigned char *stringDescriptors[] = {
     langDesc,
     productStringDescriptor,
     snifferConfigStringDescriptor,
@@ -173,7 +173,7 @@ typedef struct _SIMTraceDriverConfigurationDescriptorSniffer {
 
 } __attribute__ ((packed)) SIMTraceDriverConfigurationDescriptorSniffer;
 
-const SIMTraceDriverConfigurationDescriptorSniffer configurationDescriptorSniffer = {
+static const SIMTraceDriverConfigurationDescriptorSniffer configurationDescriptorSniffer = {
     /* Standard configuration descriptor */
     {
         sizeof(USBConfigurationDescriptor),
@@ -252,7 +252,7 @@ typedef struct {
 } __attribute__ ((packed)) CCIDDriverConfigurationDescriptors;
 */
 
-const CCIDDriverConfigurationDescriptors configurationDescriptorCCID = {
+static const CCIDDriverConfigurationDescriptors configurationDescriptorCCID = {
 
     // Standard USB configuration descriptor
     {
@@ -349,7 +349,7 @@ typedef struct _SIMTraceDriverConfigurationDescriptorPhone {
     USBEndpointDescriptor       phone_interruptIn;
 } __attribute__ ((packed)) SIMTraceDriverConfigurationDescriptorPhone;
 
-const SIMTraceDriverConfigurationDescriptorPhone configurationDescriptorPhone = {
+static const SIMTraceDriverConfigurationDescriptorPhone configurationDescriptorPhone = {
     /* Standard configuration descriptor */
     {
         sizeof(USBConfigurationDescriptor),
@@ -429,7 +429,7 @@ typedef struct _SIMTraceDriverConfigurationDescriptorMITM {
 
 } __attribute__ ((packed)) SIMTraceDriverConfigurationDescriptorMITM;
 
-const SIMTraceDriverConfigurationDescriptorMITM configurationDescriptorMITM = {
+static const SIMTraceDriverConfigurationDescriptorMITM configurationDescriptorMITM = {
     /* Standard configuration descriptor */
     {
         sizeof(USBConfigurationDescriptor),
@@ -587,7 +587,7 @@ const USBConfigurationDescriptor *configurationDescriptorsArr[] = {
 };
 
 /* AT91SAM3S only supports full speed, but not high speed USB */
-const USBDDriverDescriptors driverDescriptors = {
+static const USBDDriverDescriptors driverDescriptors = {
     &deviceDescriptor,
     (const USBConfigurationDescriptor **) &(configurationDescriptorsArr),   /* first full-speed configuration descriptor */
     0, /* No full-speed device qualifier descriptor */