diff --git a/radio/src/debug.cpp b/radio/src/debug.cpp
index 4ddcefd3e..e375015bf 100644
--- a/radio/src/debug.cpp
+++ b/radio/src/debug.cpp
@@ -47,6 +47,7 @@ void debugPrintf(const char * format, ...)
 #if defined(DEBUG_TRACE_BUFFER)
 static struct TraceElement traceBuffer[TRACE_BUFFER_LEN];
 static uint8_t traceBufferPos;
+extern Fifo<uint8_t, 512> serial2TxFifo;
 gtime_t filltm(gtime_t *t, struct gtm *tp);
 
 void trace_event(enum TraceEvent event, uint32_t data)
@@ -92,7 +93,7 @@ void dumpTraceBuffer()
     if (traceBuffer[n].time == 0 && traceBuffer[n].time_ms == 0) break;
 #if !defined(SIMU)
     if ((n % 5) == 0) {
-      while (!serial2TxFifo.empty()) {
+      while (!serial2TxFifo.isEmpty()) {
         CoTickDelay(1);
       }
     }