diff --git a/firmware/debug.c b/firmware/debug.c
index 6c688abb06..23ba8f8117 100644
--- a/firmware/debug.c
+++ b/firmware/debug.c
@@ -22,8 +22,8 @@
 #include <stdarg.h>
 #include "config.h"
 
-char debugmembuf[100];
-char debugbuf[200];
+static char debugmembuf[100];
+static char debugbuf[200];
 
 #ifndef SIMULATOR /* allow non archos platforms to display output */