diff --git a/include/stdlib.h b/include/stdlib.h
index 697605aa2566..27c6613b9fb7 100644
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: stdlib.h,v 1.110 2014/06/18 17:48:22 christos Exp $	*/
+/*	$NetBSD: stdlib.h,v 1.111 2015/01/16 18:40:16 christos Exp $	*/
 
 /*-
  * Copyright (c) 1990, 1993
@@ -123,6 +123,10 @@ double	 strtod(const char * __restrict, char ** __restrict);
 long	 strtol(const char * __restrict, char ** __restrict, int);
 unsigned long
 	 strtoul(const char * __restrict, char ** __restrict, int);
+#ifdef _OPENBSD_SOURCE
+long long strtonum(const char * __restrict, long long, long long,
+    const char ** __restrict);
+#endif
 int	 system(const char *);
 
 /* These are currently just stubs. */