diff --git a/module_usb_audio/usb_buffer/usb_buffer.xc b/module_usb_audio/usb_buffer/usb_buffer.xc
index 117ef82c..897b0fe4 100644
--- a/module_usb_audio/usb_buffer/usb_buffer.xc
+++ b/module_usb_audio/usb_buffer/usb_buffer.xc
@@ -54,9 +54,9 @@ static inline void swap(xc_ptr &a, xc_ptr &b)
 #endif
 
 #ifdef MIDI
-unsigned int g_midi_to_host_buffer_A[MAX_USB_MIDI_PACKET_SIZE/4+4];
-unsigned int g_midi_to_host_buffer_B[MAX_USB_MIDI_PACKET_SIZE/4+4];
-unsigned int g_midi_from_host_buffer[MAX_USB_MIDI_PACKET_SIZE/4+4];
+static unsigned int g_midi_to_host_buffer_A[MAX_USB_MIDI_PACKET_SIZE/4+4];
+static unsigned int g_midi_to_host_buffer_B[MAX_USB_MIDI_PACKET_SIZE/4+4];
+static unsigned int g_midi_from_host_buffer[MAX_USB_MIDI_PACKET_SIZE/4+4];
 #endif
 
 #ifdef IAP