diff --git a/lib/isc/include/isc/Makefile.in b/lib/isc/include/isc/Makefile.in
index 9577e4bd9e..646179792d 100644
--- a/lib/isc/include/isc/Makefile.in
+++ b/lib/isc/include/isc/Makefile.in
@@ -21,7 +21,7 @@ VERSION=@BIND9_VERSION@
 HEADERS =	aes.h app.h assertions.h atomic.h backtrace.h \
 		base32.h base64.h bind9.h buffer.h bufferlist.h \
 		commandline.h counter.h crc64.h deprecated.h \
-		errno.h error.h event.h eventclass.h \
+		endian.h errno.h error.h event.h eventclass.h \
 		file.h formatcheck.h fsaccess.h fuzz.h \
 		hash.h heap.h hex.h hmac.h ht.h httpd.h \
 		interfaceiter.h iterated_hash.h \
diff --git a/lib/isc/include/isc/endian.h b/lib/isc/include/isc/endian.h
new file mode 100644
index 0000000000..35ea578b33
--- /dev/null
+++ b/lib/isc/include/isc/endian.h
@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+#pragma once
+
+#if defined(__linux__) || defined(__CYGWIN__)
+
+#include <endian.h>
+
+#elif defined __APPLE__
+
+#include <libkern/OSByteOrder.h>
+
+# define htobe16(x) OSSwapHostToBigInt16(x)
+# define htole16(x) OSSwapHostToLittleInt16(x)
+# define be16toh(x) OSSwapBigToHostInt16(x)
+# define le16toh(x) OSSwapLittleToHostInt16(x)
+
+# define htobe32(x) OSSwapHostToBigInt32(x)
+# define htole32(x) OSSwapHostToLittleInt32(x)
+# define be32toh(x) OSSwapBigToHostInt32(x)
+# define le32toh(x) OSSwapLittleToHostInt32(x)
+
+# define htobe64(x) OSSwapHostToBigInt64(x)
+# define htole64(x) OSSwapHostToLittleInt64(x)
+# define be64toh(x) OSSwapBigToHostInt64(x)
+# define le64toh(x) OSSwapLittleToHostInt64(x)
+
+# define __BYTE_ORDER    BYTE_ORDER
+# define __BIG_ENDIAN    BIG_ENDIAN
+# define __LITTLE_ENDIAN LITTLE_ENDIAN
+# define __PDP_ENDIAN    PDP_ENDIAN
+
+#elif defined(__NetBSD__) || defined(__FreeBSD__) || defined(__DragonFly__)
+
+# include <sys/endian.h>
+
+# define be16toh(x) betoh16(x)
+# define le16toh(x) letoh16(x)
+
+# define be32toh(x) betoh32(x)
+# define le32toh(x) letoh32(x)
+
+# define be64toh(x) betoh64(x)
+# define le64toh(x) letoh64(x)
+
+#elif defined(_WIN32)
+/* Windows is always little endian */
+
+#include <stdlib.h>
+
+# define htobe16(x) _byteswap_ushort(x)
+# define htole16(x) (x)
+# define be16toh(x) _byteswap_ushort(x)
+# define le16toh(x) (x)
+
+# define htobe32(x) _byteswap_ulong(x)
+# define htole32(x) (x)
+# define be32toh(x) _byteswap_ulong(x)
+# define le32toh(x) (x)
+
+# define htobe64(x) _byteswap_uint64(x)
+# define htole64(x) (x)
+# define be64toh(x) _byteswap_uint64(x)
+# define le64toh(x) (x)
+
+# define __BYTE_ORDER    BYTE_ORDER
+# define __BIG_ENDIAN    BIG_ENDIAN
+# define __LITTLE_ENDIAN LITTLE_ENDIAN
+# define __PDP_ENDIAN    PDP_ENDIAN
+
+#else
+
+#error Platform not supported
+
+#endif