diff --git a/headers/os/support/Debug.h b/headers/os/support/Debug.h
index d9192a9426..5a010769de 100644
--- a/headers/os/support/Debug.h
+++ b/headers/os/support/Debug.h
@@ -47,10 +47,10 @@ extern "C" {
 										PRINT(("%s\t", #OBJ));	\
 										(OBJ).PrintToStream(); 	\
 									} ((void)0)
-	#define TRACE()					_debugPrintf("File: %s, Line: %d, Thread: %d\n", \
+	#define TRACE()					_debugPrintf("File: %s, Line: %d, Thread: %ld\n", \
 										__FILE__, __LINE__, find_thread(NULL))
 
-	#define SERIAL_TRACE()			_sPrintf("File: %s, Line: %d, Thread: %d\n", \
+	#define SERIAL_TRACE()			_sPrintf("File: %s, Line: %d, Thread: %ld\n", \
 										__FILE__, __LINE__, find_thread(NULL))
 
 	#define DEBUGGER(MSG)			if (_rtDebugFlag) debugger(MSG)