diff --git a/firmware/common/hackrf_core.h b/firmware/common/hackrf_core.h
index 37722b1c..7eb57698 100644
--- a/firmware/common/hackrf_core.h
+++ b/firmware/common/hackrf_core.h
@@ -200,6 +200,11 @@ extern "C"
 
 /* TODO add other Pins */
 
+typedef enum {
+	TRANSCEIVER_MODE_RX,
+	TRANSCEIVER_MODE_TX,
+} transceiver_mode_t;
+
 void delay(uint32_t duration);
 
 void cpu_clock_init(void);
diff --git a/firmware/usb_performance/usb_performance.c b/firmware/usb_performance/usb_performance.c
index b5eaa6fa..a4f7fd0d 100644
--- a/firmware/usb_performance/usb_performance.c
+++ b/firmware/usb_performance/usb_performance.c
@@ -38,11 +38,7 @@
 #include "usb_descriptor.h"
 #include "usb_standard_request.h"
 
-typedef enum {
-	TRANSCEIVER_MODE_RX,
-	TRANSCEIVER_MODE_TX,
-} transceiver_mode_t;
-static transceiver_mode_t transceiver_mode = TRANSCEIVER_MODE_TX;
+static volatile transceiver_mode_t transceiver_mode = TRANSCEIVER_MODE_TX;
 
 uint8_t* const usb_bulk_buffer = (uint8_t*)0x20004000;
 static volatile uint32_t usb_bulk_buffer_offset = 0;