diff --git a/armsrc/appmain.c b/armsrc/appmain.c
index a8089cf5f..135bcb081 100644
--- a/armsrc/appmain.c
+++ b/armsrc/appmain.c
@@ -20,6 +20,7 @@
 #include "fpga.h"
 #include "fpgaloader.h"
 #include "string.h"
+#include "printf.h"
 #include "legicrf.h"
 #include "BigBuf.h"
 #include "iso14443a.h"