diff --git a/hermit/libkern/printf.c b/hermit/libkern/printf.c
index 2284666fb..e1345b91f 100644
--- a/hermit/libkern/printf.c
+++ b/hermit/libkern/printf.c
@@ -46,6 +46,7 @@
 
 #include <hermit/string.h>
 
+/* HermitCore use only the 64bit version */
 #define __64BIT__
 
 #ifdef __64BIT__
@@ -63,7 +64,7 @@ typedef unsigned long long u_quad_t;
 typedef long long quad_t;
 typedef unsigned long uintptr_t;
 #define NBBY    8		/* number of bits in a byte */
-char const hex2ascii_data[] = "0123456789abcdefghijklmnopqrstuvwxyz";
+static char const hex2ascii_data[] = "0123456789abcdefghijklmnopqrstuvwxyz";
 #define hex2ascii(hex)  (hex2ascii_data[hex])
 #define va_list __builtin_va_list
 #define va_start __builtin_va_start