1 files changed, 3 insertions, 0 deletions
diff --git a/lib/libc/include/stdio.h b/lib/libc/include/stdio.h
index b19230c..e701de0 100644
--- a/lib/libc/include/stdio.h
+++ b/lib/libc/include/stdio.h
@@ -31,6 +31,7 @@
 #define _STDIO_H
 
 #include <stddef.h>
+#include <stdarg.h>
 
 #define EOF (int)-1
 
@@ -64,4 +65,6 @@ int puts(const char *s);
 int fflush(FILE *stream);
 int fclose(FILE *stream);
 
+int vsnprintf(char *s, size_t size, const char *fmt, va_list ap);
+
 #endif  /* !_STDIO_H */