diff --git a/firmware/src_simtrace/main.c b/firmware/src_simtrace/main.c
index 1454e027..a1058e18 100644
--- a/firmware/src_simtrace/main.c
+++ b/firmware/src_simtrace/main.c
@@ -51,7 +51,17 @@ static const conf_func config_func_ptrs[] = {
 /*------------------------------------------------------------------------------
  *         Internal variables
  *------------------------------------------------------------------------------*/
-volatile enum confNum simtrace_config = CFG_NUM_SNIFF;
+static volatile enum confNum simtrace_config = CFG_NUM_SNIFF;
+
+/*----------------------------------------------------------------------------
+ *       Callbacks
+ *----------------------------------------------------------------------------*/
+
+void USBDDriverCallbacks_ConfigurationChanged(uint8_t cfgnum)
+{
+    TRACE_INFO_WP("cfgChanged%d ", cfgnum);
+    simtrace_config = cfgnum;
+}
 
 /*------------------------------------------------------------------------------
  *        Main
diff --git a/firmware/src_simtrace/simtrace.h b/firmware/src_simtrace/simtrace.h
index ea2d401f..00d2b738 100644
--- a/firmware/src_simtrace/simtrace.h
+++ b/firmware/src_simtrace/simtrace.h
@@ -29,7 +29,6 @@ extern volatile ringbuf sim_rcv_buf;
 
 extern volatile bool rcvdChar;
 extern volatile uint32_t char_stat;
-extern volatile enum confNum simtrace_config;
 
 extern const Pin pinPhoneRST;
 
diff --git a/firmware/src_simtrace/usb.c b/firmware/src_simtrace/usb.c
index 9555003b..be1933c8 100644
--- a/firmware/src_simtrace/usb.c
+++ b/firmware/src_simtrace/usb.c
@@ -595,17 +595,6 @@ const USBDDriverDescriptors driverDescriptors = {
 };
 
 
-/*----------------------------------------------------------------------------
- *       Callbacks
- *----------------------------------------------------------------------------*/
-
-void USBDDriverCallbacks_ConfigurationChanged(uint8_t cfgnum)
-{
-    TRACE_INFO_WP("cfgChanged%d ", cfgnum);
-    simtrace_config = cfgnum;
-}
-
-
 /*----------------------------------------------------------------------------
  *        Functions 
  *----------------------------------------------------------------------------*/