diff --git a/include/kernel/io.h b/include/kernel/io.h
index 136c4f9..718bb20 100644
--- a/include/kernel/io.h
+++ b/include/kernel/io.h
@@ -28,6 +28,9 @@
 int strcmp(char *a, char *b);
 uint strlen(char *a);
 
+bool isdigit(char c);
+uint parse_int(char *string);
+
 uchar kbd_scan_code();
 void kbd_handle_input(struct registers *registers);
 void init_kbd();