diff --git a/apps/debug_menu.c b/apps/debug_menu.c
index 3788631c81..f93755a293 100644
--- a/apps/debug_menu.c
+++ b/apps/debug_menu.c
@@ -2367,7 +2367,7 @@ static bool dbg_scrollwheel(void)
 }
 #endif
 
-#if defined(HAVE_USBSTACK) && defined(ROCKBOX_HAS_LOGF)
+#if defined(HAVE_USBSTACK) && defined(ROCKBOX_HAS_LOGF) && defined(USB_SERIAL)
 static bool logf_usb_serial(void)
 {
     bool serial_enabled = !usb_core_driver_enabled(USB_DRIVER_SERIAL);
@@ -2457,7 +2457,7 @@ static const struct the_menu_item menuitems[] = {
         {"logf", logfdisplay },
         {"logfdump", logfdump },
 #endif
-#if defined(HAVE_USBSTACK) && defined(ROCKBOX_HAS_LOGF)
+#if defined(HAVE_USBSTACK) && defined(ROCKBOX_HAS_LOGF) && defined(USB_SERIAL)
         {"logf over usb",logf_usb_serial },
 #endif
 #ifdef CPU_BOOST_LOGGING
diff --git a/firmware/usbstack/usb_core.c b/firmware/usbstack/usb_core.c
index ff54e4269f..e0aaa9b2f4 100644
--- a/firmware/usbstack/usb_core.c
+++ b/firmware/usbstack/usb_core.c
@@ -183,10 +183,10 @@ static enum { DEFAULT, ADDRESS, CONFIGURED } usb_state;
 
 static int usb_core_num_interfaces;
 
-int usb_charging_get_config_descriptor(unsigned char *dest,int max_packet_size,
-                                            int interface_number,int endpoint);
+static int usb_charging_get_config_descriptor(unsigned char *dest,int max_packet_size,
+                                              int interface_number,int endpoint);
 
-struct usb_class_driver drivers[] =
+static struct usb_class_driver drivers[USB_NUM_DRIVERS] =
 {
 #ifdef USB_STORAGE
     [USB_DRIVER_MASS_STORAGE] = {
@@ -325,7 +325,7 @@ void usb_core_init(void)
     logf("usb_core_init() finished");
 }
 
-int usb_charging_get_config_descriptor(unsigned char *dest,int max_packet_size,
+static int usb_charging_get_config_descriptor(unsigned char *dest,int max_packet_size,
                                             int interface_number,int endpoint)
 {
     (void) max_packet_size;