diff --git a/src/unistd/_exit.c b/src/unistd/_exit.c
index c7199fa..8d69e63 100644
--- a/src/unistd/_exit.c
+++ b/src/unistd/_exit.c
@@ -1,4 +1,7 @@
 #include <unistd.h>
 
 /* Exit immediately, bypassing exit handlers or signal handlers. */
+extern void _Exit(int status);
+
+/* Alias to _Exit. */
 void _exit(int status) __attribute__((alias("_Exit")));