diff --git a/include/libc/vsprintf.h b/include/libc/vsprintf.h
index b760224..cd28fb3 100644
--- a/include/libc/vsprintf.h
+++ b/include/libc/vsprintf.h
@@ -18,7 +18,11 @@
 #define _H_VSPRINTF
 
 #include <stdarg.h>
+#include "openbios/config.h"
+
 extern int	vsprintf(char *buf, const char *fmt, va_list args );
 extern int	sprintf(char * buf, const char *fmt, ...);
+extern int vsnprintf(char *buf, size_t size, const char *fmt, va_list args);
+extern int snprintf(char * buf, size_t size, const char *fmt, ...);
 
 #endif   /* _H_VSPRINTF */