diff --git a/include/tty.h b/include/tty.h
index 9f577aa..6ec7d33 100644
--- a/include/tty.h
+++ b/include/tty.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <stddef.h>
+#include <stdarg.h>
 
 int putchar(int c);