diff --git a/libc/private/isc/assertions.h b/libc/private/isc/assertions.h
new file mode 100644
index 0000000..921d18f
--- /dev/null
+++ b/libc/private/isc/assertions.h
@@ -0,0 +1,124 @@
+/*	$NetBSD: assertions.h,v 1.1.1.1 2004/05/20 19:49:41 christos Exp $	*/
+
+/*
+ * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
+ * Copyright (c) 1997-1999 by Internet Software Consortium.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
+ * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * Id: assertions.h,v 1.1.206.1 2004/03/09 08:33:30 marka Exp
+ */
+
+#ifndef ASSERTIONS_H
+#define ASSERTIONS_H		1
+
+typedef enum {
+	assert_require, assert_ensure, assert_insist, assert_invariant
+} assertion_type;
+
+typedef void (*assertion_failure_callback)(const char *, int, assertion_type,
+					   const char *, int);
+
+extern assertion_failure_callback __assertion_failed;
+void set_assertion_failure_callback(assertion_failure_callback f);
+const char *assertion_type_to_text(assertion_type type);
+
+#ifdef CHECK_ALL
+#define CHECK_REQUIRE		1
+#define CHECK_ENSURE		1
+#define CHECK_INSIST		1
+#define CHECK_INVARIANT		1
+#endif
+
+#ifdef CHECK_NONE
+#define CHECK_REQUIRE		0
+#define CHECK_ENSURE		0
+#define CHECK_INSIST		0
+#define CHECK_INVARIANT		0
+#endif
+
+#ifndef CHECK_REQUIRE
+#define CHECK_REQUIRE		1
+#endif
+
+#ifndef CHECK_ENSURE
+#define CHECK_ENSURE		1
+#endif
+
+#ifndef CHECK_INSIST
+#define CHECK_INSIST		1
+#endif
+
+#ifndef CHECK_INVARIANT
+#define CHECK_INVARIANT		1
+#endif
+
+#if CHECK_REQUIRE != 0
+#define REQUIRE(cond) \
+	((void) ((cond) || \
+		 ((__assertion_failed)(__FILE__, __LINE__, assert_require, \
+				       #cond, 0), 0)))
+#define REQUIRE_ERR(cond) \
+	((void) ((cond) || \
+		 ((__assertion_failed)(__FILE__, __LINE__, assert_require, \
+				       #cond, 1), 0)))
+#else
+#define REQUIRE(cond)		((void) (cond))
+#define REQUIRE_ERR(cond)	((void) (cond))
+#endif /* CHECK_REQUIRE */
+
+#if CHECK_ENSURE != 0
+#define ENSURE(cond) \
+	((void) ((cond) || \
+		 ((__assertion_failed)(__FILE__, __LINE__, assert_ensure, \
+				       #cond, 0), 0)))
+#define ENSURE_ERR(cond) \
+	((void) ((cond) || \
+		 ((__assertion_failed)(__FILE__, __LINE__, assert_ensure, \
+				       #cond, 1), 0)))
+#else
+#define ENSURE(cond)		((void) (cond))
+#define ENSURE_ERR(cond)	((void) (cond))
+#endif /* CHECK_ENSURE */
+
+#if CHECK_INSIST != 0
+#define INSIST(cond) \
+	((void) ((cond) || \
+		 ((__assertion_failed)(__FILE__, __LINE__, assert_insist, \
+				       #cond, 0), 0)))
+#define INSIST_ERR(cond) \
+	((void) ((cond) || \
+		 ((__assertion_failed)(__FILE__, __LINE__, assert_insist, \
+				       #cond, 1), 0)))
+#else
+#define INSIST(cond)		((void) (cond))
+#define INSIST_ERR(cond)	((void) (cond))
+#endif /* CHECK_INSIST */
+
+#if CHECK_INVARIANT != 0
+#define INVARIANT(cond) \
+	((void) ((cond) || \
+		 ((__assertion_failed)(__FILE__, __LINE__, assert_invariant, \
+				       #cond, 0), 0)))
+#define INVARIANT_ERR(cond) \
+	((void) ((cond) || \
+		 ((__assertion_failed)(__FILE__, __LINE__, assert_invariant, \
+				       #cond, 1), 0)))
+#else
+#define INVARIANT(cond)		((void) (cond))
+#define INVARIANT_ERR(cond)	((void) (cond))
+#endif /* CHECK_INVARIANT */
+
+#endif /* ASSERTIONS_H */