diff --git a/libc/include/err.h b/libc/include/err.h
index e69de29..1636efe 100644
--- a/libc/include/err.h
+++ b/libc/include/err.h
@@ -0,0 +1,90 @@
+/*	$OpenBSD: err.h,v 1.10 2006/01/06 18:53:04 millert Exp $	*/
+/*	$NetBSD: err.h,v 1.11 1994/10/26 00:55:52 cgd Exp $	*/
+
+/*-
+ * Copyright (c) 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *	@(#)err.h	8.1 (Berkeley) 6/2/93
+ */
+
+#ifndef _ERR_H_
+#define	_ERR_H_
+
+/*
+ * Don't use va_list in the err/warn prototypes.   Va_list is typedef'd in two
+ * places (<machine/varargs.h> and <machine/stdarg.h>), so if we include one
+ * of them here we may collide with the utility's includes.  It's unreasonable
+ * for utilities to have to include one of them to include err.h, so we get
+ * __va_list from <machine/_types.h> and use it.
+ */
+#include <sys/cdefs.h>
+#include <machine/_types.h>
+
+__BEGIN_DECLS
+
+__noreturn void	err(int, const char *, ...)
+			__attribute__((__format__ (printf, 2, 3)));
+__noreturn void	verr(int, const char *, __va_list)
+			__attribute__((__format__ (printf, 2, 0)));
+__noreturn void	errx(int, const char *, ...)
+			__attribute__((__format__ (printf, 2, 3)));
+__noreturn void	verrx(int, const char *, __va_list)
+			__attribute__((__format__ (printf, 2, 0)));
+void		warn(const char *, ...)
+			__attribute__((__format__ (printf, 1, 2)));
+void		vwarn(const char *, __va_list)
+			__attribute__((__format__ (printf, 1, 0)));
+void		warnx(const char *, ...)
+			__attribute__((__format__ (printf, 1, 2)));
+void		vwarnx(const char *, __va_list)
+			__attribute__((__format__ (printf, 1, 0)));
+
+/*
+ * The _* versions are for use in library functions so user-defined
+ * versions of err*,warn* do not get used.
+ */
+__noreturn void	_err(int, const char *, ...)
+			__attribute__((__format__ (printf, 2, 3)));
+__noreturn void	_verr(int, const char *, __va_list)
+			__attribute__((__format__ (printf, 2, 0)));
+__noreturn void	_errx(int, const char *, ...)
+			__attribute__((__format__ (printf, 2, 3)));
+__noreturn void	_verrx(int, const char *, __va_list)
+			__attribute__((__format__ (printf, 2, 0)));
+void		_warn(const char *, ...)
+			__attribute__((__format__ (printf, 1, 2)));
+void		_vwarn(const char *, __va_list)
+			__attribute__((__format__ (printf, 1, 0)));
+void		_warnx(const char *, ...)
+			__attribute__((__format__ (printf, 1, 2)));
+void		_vwarnx(const char *, __va_list)
+			__attribute__((__format__ (printf, 1, 0)));
+
+__END_DECLS
+
+#endif /* !_ERR_H_ */