diff --git a/libc/include/signal.h b/libc/include/signal.h
index 5540847..9e5ce61 100644
--- a/libc/include/signal.h
+++ b/libc/include/signal.h
@@ -118,6 +118,7 @@
 
 extern int raise(int);
 extern int kill(pid_t, int);
+extern int killpg(int pgrp, int sig);
 
 
 __END_DECLS