diff --git a/src/system/flashtool.cpp b/src/system/flashtool.cpp
index 13f4a4580..395b5a411 100644
--- a/src/system/flashtool.cpp
+++ b/src/system/flashtool.cpp
@@ -38,6 +38,10 @@
 
 #include <global.h>
 
+#if HAVE_TRIPLEDRAGON
+/* TD kernel 2.6.12 is too old and does not have writesize yet, use oobsize instead */
+#define writesize oobsize
+#endif
 
 CFlashTool::CFlashTool()
 {